20-F/A

As filed with the Securities and Exchange Commission on May 4, 2018

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 20-F/A

AMENDMENT NO. 1

(Mark One)

☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934

OR

☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2017

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

OR

☐ SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of event requiring this shell company report

For the transition period from            to            

Commission file number 1-14418

SK Telecom Co., Ltd.

(Exact name of Registrant as specified in its charter)

SK Telecom Co., Ltd.

(Translation of Registrant’s name into English)

The Republic of Korea

(Jurisdiction of incorporation or organization)

SK T-Tower

65, Eulji-ro, Jung-gu, Seoul, Korea

(Address of principal executive offices)

Ms. Min Joo Kim

65, Eulji-ro, Jung-gu, Seoul, Korea

Telephone No.: 82-2-6100-2114

Facsimile No.: 82-2-6100-7830

(Name, telephone, email and/or facsimile number and address of company contact person)

Securities registered or to be registered pursuant to Section 12(b) of the Act.

Title of Each Class	Name of Each Exchange on Which Registered
American Depositary Shares, each representing one-ninth of one share of Common Stock	New York Stock Exchange
Common Stock, par value ￦500 per share	New York Stock Exchange*

* Not for trading, but only in connection with the registration of the American Depositary Shares.

Securities registered or to be registered pursuant to Section 12(g) of the Act.

None

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act.

None

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

70,609,160 shares of common stock, par value ￦500 per share (not including 10,136,551 shares of common stock held by the company as treasury shares).

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ☑    No  ☐

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.    Yes  ☐    No  ☑

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☑    No  ☐

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ☑    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or an emerging growth company. See definitions of “accelerated filer,” “large accelerated filer” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer  ☑            Accelerated filer  ☐            Non-accelerated filer  ☐            Emerging growth company  ☐

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP  ☐     International Financial Reporting Standards as issued by the International Accounting Standards Board  ☑     Other  ☐

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Indicate by check mark which financial statement item the registrant has elected to follow. Item 17  ☐     Item 18  ☑

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☑

EXPLANATORY NOTE

SK Telecom Co., Ltd. is filing this Amendment No. 1 (this “Form 20-F/A”) to its annual report on Form 20-F (the “Form 20-F”) for the fiscal year ended December 31, 2017, which was originally filed with the U.S. Securities and Exchange Commission on April 27, 2018, to:

• submit its Interactive Data File (as defined in Rule 11 of Regulation S-T) with respect to the audited consolidated financial statements of SK Telecom Co., Ltd. for that fiscal year as an exhibit to the Form 20-F pursuant to paragraph 101 under “Instructions as to Exhibits” of Form 20-F in accordance with Rule 405 of Regulation S-T; and

• correct typographical errors in Item 16.G. “Corporate Governance.”

Other than as expressly set forth above, this Form 20-F/A does not, and does not purport to, amend, update or restate the information in the Form 20-F in any way or reflect any events that have occurred after the Form 20-F was originally filed. The Form 20-F, as amended by this Form 20-F/A, continues to speak as of the initial filing date of the Form 20-F. Accordingly, this Form 20-F/A should be read in conjunction with the Form 20-F.

Item 16. RESERVED

Item 16.G. CORPORATE GOVERNANCE

The following is a summary of the significant differences between the NYSE’s corporate governance standards and those that we follow under Korean law.

NYSE Corporate Governance Standards	Our Corporate Governance Practice
Director Independence
Listed companies must have a majority of independent directors.	Of the eight members of our board of directors, five are independent directors.
Executive Session
Non-management directors must meet in regularly scheduled executive sessions without management. Independent directors should meet alone in an executive session at least once a year.	Our audit committee, which is comprised solely of four independent directors, holds meetings whenever there are matters related to management directors, and such meetings are generally held once every month.
Nomination/Corporate Governance Committee
Listed companies must have a nomination/corporate governance committee composed entirely of independent directors. The committee must have a charter that addresses the purpose, responsibilities (including development of corporate governance guidelines) and annual performance evaluation of the committee.	Although we do not have a separate nomination/ corporate governance committee, we maintain an independent director nomination committee composed of two independent directors and one management director.
Compensation Committee
Listed companies must have a compensation committee composed entirely of independent directors. The committee must have a charter that addresses the purpose, responsibilities and annual performance evaluation of the committee. The charter must be made available on the company’s website. In addition, in accordance with the U.S. Securities and Exchange Commission rules adopted pursuant to Section 952 of the Dodd-Frank Act, the New York Stock Exchange listing standards were amended to expand the factors relevant in determining whether a committee member has a relationship with the company	We maintain a compensation review committee comprised of three independent directors.

NYSE Corporate Governance Standards	Our Corporate Governance Practice
that will materially affect that member’s duties to the compensation committee.
Audit Committee
Listed companies must have an audit committee that satisfies the independence and other requirements of Rule 10A-3 under the Exchange Act. All members must be independent. The committee must have a charter addressing the committee’s purpose, an annual performance evaluation of the committee, and the duties and responsibilities of the committee. The charter must be made available on the company’s website.	We maintain an audit committee comprised solely of four independent directors.
Audit Committee Additional Requirements
Listed companies must have an audit committee that is composed of at least three directors.	Our audit committee has four independent directors.
Shareholder Approval of Equity Compensation Plan
Listed companies must allow its shareholders to exercise their voting rights with respect to any material revision to the company’s equity compensation plan.	We currently have two equity compensation plans: a stock option plan for officers and directors and employee stock ownership plan for employees (“ESOP”). We manage such compensation plans in compliance with the applicable laws and our articles of incorporation, provided that, under certain limited circumstances, the grant of stock options or matters relating to ESOP are not subject to shareholders’ approval under Korean law.
Corporate Governance Guidelines
Listed companies must adopt and disclose corporate governance guidelines.	Although we do not maintain separate corporate governance guidelines, we are in compliance with the Korean Commercial Code in connection with such matters, including the governance of the board of directors.
Code of Business Conduct and Ethics
Listed companies must adopt and disclose a code of business conduct and ethics for directors, officers and employees and promptly disclose any waivers of the code for directors or executive officers.	We have adopted a Code of Business Conduct and Ethics for all of our directors, officers and employees, and such code is also available on our website at www.sktelecom.com.

PART III

Item 19. EXHIBITS

Number	Description
101.INS*	XBRL Instance Document
101.SCH*	XBRL Taxonomy Extension Schema Document
101.CAL*	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF*	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB*	XBRL Taxonomy Extension Label Linkbase Document
101.PRE*	XBRL Taxonomy Extension Presentation Linkbase Document

* In accordance with Rule 406T(b)(2) of Regulation S-T, such XBRL information will be furnished and not filed or part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, as amended, will be deemed not filed for purposes of Section 18 of the Exchange Act of 1934, as amended, and otherwise will not be subject to liability under those sections.

SIGNATURE

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F and that it has duly caused and authorized the undersigned to sign this Amendment No. 1 to its annual report on Form 20-F on its behalf.

SK TELECOM CO., LTD.

(Registrant)

/s/    Jeong Hwan Choi
Name:	Jeong Hwan Choi
Title:	Senior Vice President, IRO

Date: May 4, 2018

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Document and Entity Information	12 Months Ended
	Dec. 31, 2017 shares
Document - Document and Entity Information [Abstract]
Document Type	20-F/A
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	SKM
Entity Registrant Name	SK TELECOM CO LTD
Entity Central Index Key	0001015650
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	70,609,160

XML

Consolidated Statements of Financial Position - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	₩ 1,457,735	₩ 1,505,242
Short-term financial instruments	616,780	468,768
Short-term investment securities	144,386	107,364
Accounts receivable - trade, net	2,126,007	2,240,926
Short-term loans, net	62,830	58,979
Accounts receivable - other, net	1,260,835	1,121,444
Prepaid expenses	197,046	169,173
Inventories, net	272,403	259,846
Advanced payments and other	63,777	64,886
Total Current Assets	6,201,799	5,996,628
Non-Current Assets:
Long-term financial instruments	1,222	937
Long-term investment securities	887,007	828,521
Investments in associates and joint ventures	9,538,438	7,404,323
Property and equipment, net	10,144,882	10,374,212
Goodwill	1,915,017	1,932,452
Intangible assets, net	3,586,965	3,776,354
Long-term loans, net	50,874	65,476
Long-term accounts receivable - other	287,048	149,669
Long-term prepaid expenses	90,834	88,130
Guarantee deposits	292,590	298,964
Long-term derivative financial assets	253,213	214,770
Defined benefit assets	45,952	30,247
Deferred tax assets	88,132	75,111
Other non-current assets	44,696	61,869
Total Non-Current Assets	27,226,870	25,301,035
Total Assets	33,428,669	31,297,663
Current Liabilities:
Short-term borrowings	130,000	2,614
Current portion of long-term debt, net	1,530,948	888,467
Current portion of long-term payables - other	302,703	301,773
Accounts payable - trade	351,711	402,445
Accounts payable - other	1,867,074	1,767,799
Withholdings	961,501	964,084
Accrued expenses	1,327,906	1,125,816
Income tax payable	219,791	474,931
Unearned revenue	175,732	188,403
Provisions	52,057	66,227
Receipts in advance	161,266	174,588
Derivative financial liabilities	28,406	86,950
Other current liabilities	28	2
Total Current Liabilities	7,109,123	6,444,099
Non-Current Liabilities:
Debentures, excluding current portion, net	5,596,570	6,338,930
Long-term borrowings, excluding current portion	211,486	139,716
Long-term payables - other	1,346,763	1,624,590
Long-term unearned revenue	7,052	2,389
Defined benefit liabilities	61,960	70,739
Long-term derivative financial liabilities	11,064	203
Long-term provisions	32,669	31,690
Deferred tax liabilities	978,693	479,765
Other non-current liabilities	44,094	49,112
Total Non-Current Liabilities	8,290,351	8,737,134
Total Liabilities	15,399,474	15,181,233
Shareholders' Equity
Share capital	44,639	44,639
Capital deficit and others	(202,237)	(198,739)
Hybrid bonds	398,518	398,518
Retained earnings	17,835,946	15,953,164
Reserves	(234,727)	(226,183)
Equity attributable to owners of the Parent Company	17,842,139	15,971,399
Non-controlling interests	187,056	145,031
Total Shareholders' Equity	18,029,195	16,116,430
Total Liabilities and Shareholders' Equity	₩ 33,428,669	₩ 31,297,663

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Consolidated Statements of Income - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating revenue and other income:
Revenue	₩ 17,520,013	₩ 17,091,816	₩ 17,136,734
Other income	31,997	66,548	30,935
Operating revenue and other income	17,552,010	17,158,364	17,167,669
Operating expenses:
Labor	1,966,156	1,869,763	1,893,745
Commissions	5,486,263	5,376,726	5,206,951
Depreciation and amortization	3,097,466	2,941,886	2,845,295
Network interconnection	875,045	954,267	957,605
Leased line	342,240	394,412	389,819
Advertising	522,753	438,453	405,005
Rent	520,244	517,305	493,586
Cost of products that have been resold	1,886,524	1,838,368	1,955,861
Others	1,630,747	1,523,766	1,524,377
Operating expenses	16,327,438	15,854,946	15,672,244
Operating profit	1,224,572	1,303,418	1,495,425
Finance income	366,561	575,050	103,900
Finance costs	(433,616)	(326,830)	(350,100)
Gain relating to investments in subsidiaries, associates and joint ventures, net	2,245,732	544,501	786,140
Profit before income tax	3,403,249	2,096,139	2,035,365
Income tax expense	745,654	436,038	519,480
Profit for the year	2,657,595	1,660,101	1,515,885
Attributable to:
Owners of the Parent Company	2,599,829	1,675,967	1,518,604
Non-controlling interests	₩ 57,766	₩ (15,866)	₩ (2,719)
Earnings per share:
Basic and diluted earnings per share (in won)	₩ 36,582	₩ 23,497	₩ 20,988

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Consolidated Statements of Comprehensive Income - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of comprehensive income [abstract]
Profit for the year	₩ 2,657,595	₩ 1,660,101	₩ 1,515,885
Items that will never be reclassified to profit or loss, net of taxes:
Remeasurement of defined benefit liabilities	5,921	(7,524)	(14,489)
Items that are or may be reclassified subsequently to profit or loss, net of taxes:
Net change in unrealized fair value of available-for-sale financial assets	158,440	(223,981)	(3,661)
Net change in other comprehensive income of investments in associates and joint ventures	(141,008)	(9,939)	(5,709)
Net change in unrealized fair value of derivatives	22,586	(13,218)	(1,271)
Foreign currency translation differences for foreign operations	(46,952)	7,331	26,965
Other comprehensive income (loss)	(1,013)	(247,331)	1,835
Total comprehensive income	2,656,582	1,412,770	1,517,720
Total comprehensive income (loss) attributable to:
Owners of the Parent Company	2,597,160	1,432,982	1,522,280
Non-controlling interests	₩ 59,422	₩ (20,212)	₩ (4,560)

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Consolidated Statements of Changes in Equity - KRW (₩) ₩ in Millions	Total	Share capital [member]	Capital surplus (deficit) and others [member]	Hybrid bonds [member]	Retained earnings [member]	Reserves [member]	Attributable to owners [member]	Non-controlling interests [member]
Balance at Dec. 31, 2014	₩ 15,248,270	₩ 44,639	₩ (120,520)	₩ 398,518	₩ 14,188,591	₩ (4,489)	₩ 14,506,739	₩ 741,531
Total comprehensive income:
Profit (loss) for the year	1,515,885				1,518,604		1,518,604	(2,719)
Other comprehensive income (loss)	1,835				(13,402)	17,078	3,676	(1,841)
Total comprehensive income	1,517,720				1,505,202	17,078	1,522,280	(4,560)
Transactions with owners:
Annual dividends	(596,008)				(595,865)		(595,865)	(143)
Interim dividends	(72,629)				(72,629)		(72,629)
Interest on hybrid bonds	(16,840)				(16,840)		(16,840)
Acquisition of treasury shares	(490,192)		(490,192)				(490,192)
Disposal of treasury shares	425,744		425,744				425,744
Changes in consolidation scope	(5,226)							(5,226)
Changes in ownership in subsidiaries	(636,743)		(24,040)		(832)	(3,286)	(28,158)	(608,585)
Transactions with owners	(1,391,894)		(88,488)		(686,166)	(3,286)	(777,940)	(613,954)
Balance at Dec. 31, 2015	15,374,096	44,639	(209,008)	398,518	15,007,627	9,303	15,251,079	123,017
Total comprehensive income:
Profit (loss) for the year	1,660,101				1,675,967		1,675,967	(15,866)
Other comprehensive income (loss)	(247,331)				(7,499)	(235,486)	(242,985)	(4,346)
Total comprehensive income	1,412,770				1,668,468	(235,486)	1,432,982	(20,212)
Transactions with owners:
Annual dividends	(635,782)				(635,482)		(635,482)	(300)
Interim dividends	(70,609)				(70,609)		(70,609)
Interest on hybrid bonds	(16,840)				(16,840)		(16,840)
Changes in ownership in subsidiaries	52,795		10,269				10,269	42,526
Transactions with owners	(670,436)		10,269		(722,931)		(712,662)	42,226
Balance at Dec. 31, 2016	16,116,430	44,639	(198,739)	398,518	15,953,164	(226,183)	15,971,399	145,031
Total comprehensive income:
Profit (loss) for the year	2,657,595				2,599,829		2,599,829	57,766
Other comprehensive income (loss)	(1,013)				5,875	(8,544)	(2,669)	1,656
Total comprehensive income	2,656,582				2,605,704	(8,544)	2,597,160	59,422
Transactions with owners:
Annual dividends	(635,763)				(635,482)		(635,482)	(281)
Interim dividends	(70,609)				(70,609)		(70,609)
Interest on hybrid bonds	(16,840)				(16,840)		(16,840)
Share option	414		414				414
Changes in ownership in subsidiaries	(21,019)		(3,912)		9		(3,903)	(17,116)
Transactions with owners	(743,817)		(3,498)		(722,922)		(726,420)	(17,397)
Balance at Dec. 31, 2017	₩ 18,029,195	₩ 44,639	₩ (202,237)	₩ 398,518	₩ 17,835,946	₩ (234,727)	₩ 17,842,139	₩ 187,056

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Consolidated Statements of Cash Flows - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash generated from operating activities
Profit for the year	₩ 2,657,595	₩ 1,660,101	₩ 1,515,885
Adjustments for income and expenses (Note 38)	2,096,764	3,039,561	3,250,143
Changes in assets and liabilities related to operating activities (Note 38)	(261,468)	13,764	(685,734)
Sub-total	4,492,891	4,713,426	4,080,294
Interest received	66,713	44,602	43,400
Dividends received	106,674	98,267	62,973
Interest paid	(234,127)	(245,236)	(275,796)
Income tax paid	(576,331)	(367,891)	(132,742)
Net cash provided by operating activities	3,855,820	4,243,168	3,778,129
Cash inflows from investing activities:
Decrease in short-term financial instruments, net		222,322
Decrease in short-term investment securities, net			105,158
Collection of short-term loans	216,700	238,980	398,308
Decrease in long-term financial instruments	27	28	7,424
Proceeds from disposals of long-term investment securities	129,726	555,519	149,310
Proceeds from disposals of investments in associates and joint ventures	5,925	66,852	185,094
Proceeds from disposals of property and equipment	29,368	22,549	36,586
Proceeds from disposals of intangible assets	8,848	16,532	3,769
Proceeds from disposals of assets held for sale			1,009
Collection of long-term loans	6,205	1,960	2,132
Decrease in deposits	24,550	14,894	14,635
Proceeds from disposals of other non-current assets	1,185	728	607
Proceeds from disposals of subsidiaries	30,132		155
Increase in cash due to merger	4,112		10,355
Receipt of government grants		300
Sub-total	456,778	1,140,664	914,542
Cash outflows for investing activities:
Increase in short-term financial instruments, net	(156,012)		(385,612)
Increase in short-term investment securities, net	(28,975)	(6,334)
Increase in short-term loans	(205,878)	(239,303)	(370,378)
Increase in long-term loans	(5,869)	(32,287)	(16,701)
Increase in long-term financial instruments	(2,034)	(342)	(10,008)
Acquisitions of long-term investment securities	(19,328)	(30,949)	(312,261)
Acquisitions of investments in associates and joint ventures	(193,100)	(130,388)	(65,080)
Acquisitions of property and equipment	(2,715,859)	(2,490,455)	(2,478,778)
Acquisitions of intangible assets	(145,740)	(635,387)	(127,948)
Increase in deposits	(26,377)	(12,943)	(12,536)
Increase in other non-current assets	(47)	(763)	(2,542)
Acquisitions of businesses, net of cash acquired		(4,498)	(13,197)
Acquisitions of subsidiaries, net of cash acquired	(26,566)	(19,032)
Liquidation of subsidiary	(1,600)	(191)
Sub-total	(3,527,385)	(3,602,872)	(3,795,041)
Net cash used in investing activities	(3,070,607)	(2,462,208)	(2,880,499)
Cash inflows from financing activities:
Proceeds from short-term borrowings, net	127,386
Proceeds from issuance of debentures	973,291	776,727	1,375,031
Proceeds from long-term borrowings	120,000	49,000
Cash inflows from settlement of derivatives	188	251	175
Cash received from transfer of interests in subsidiaries to non-controlling interests	40,938	35,646
Sub-total	1,261,803	861,624	1,375,206
Cash outflows for financing activities:
Decrease in short-term borrowings, net		(257,386)	(106,600)
Repayments of long-term account payables-other	(305,476)	(122,723)	(191,436)
Repayments of debentures	(842,733)	(770,000)	(620,000)
Repayments of long-term borrowings	(32,701)	(33,387)	(21,924)
Cash outflows from settlement of derivatives	(105,269)		(655)
Payments of finance lease liabilities		(26)	(3,206)
Payments of dividends	(706,091)	(706,091)	(668,494)
Payments of interest on hybrid bonds	(16,840)	(16,840)	(16,840)
Acquisitions of treasury shares			(490,192)
Transactions with non-controlling shareholders	(79,311)		(220,442)
Sub-total	(2,088,421)	(1,906,453)	(2,339,789)
Net cash used in financing activities	(826,618)	(1,044,829)	(964,583)
Net increase (decrease) in cash and cash equivalents	(41,405)	736,131	(66,953)
Cash and cash equivalents at beginning of the year	1,505,242	768,922	834,429
Effects of exchange rate changes on cash and cash equivalents	(6,102)	189	1,446
Cash and cash equivalents at end of the year	₩ 1,457,735	₩ 1,505,242	₩ 768,922

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Reporting Entity

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Reporting Entity

1. Reporting Entity

(1)    General

SK Telecom Co., Ltd. (“the Parent Company”) was incorporated in March 1984 under the laws of the Republic of Korea (“Korea”) to provide cellular telephone communication services in Korea. The Parent Company mainly provides wireless telecommunications services in Korea. The head office of the Parent Company is located at 65, Eulji-ro, Jung-gu, Seoul, Korea.

The Parent Company’s common shares and depositary receipts (DRs) are listed on the Stock Market of Korea Exchange, the New York Stock Exchange and the London Stock Exchange. As of December 31, 2017, the Parent Company’s total issued shares are held by the following shareholders:

	Number of shares		Percentage of total shares issued(%)
SK Holdings Co., Ltd.		20,363,452		25.22
National Pension Service		7,392,350		9.16
Institutional investors and other minority shareholders		42,853,358		53.07
Treasury shares		10,136,551		12.55
Total number of shares		80,745,711		100.00

These consolidated financial statements comprise the Parent Company and its subsidiaries (together referred to as the “Group” and individuals as “Group entities”). SK Holdings Co., Ltd. is the ultimate controlling entity of the Parent Company.

(2)    List of subsidiaries

The list of subsidiaries as of December 31, 2017 and 2016 is as follows:

				Ownership (%)(*1)
Subsidiary		Location	Primary business	Dec. 31, 2017		Dec. 31, 2016
Subsidiaries owned by the Parent Company	SK Telink Co., Ltd.(*2)	Korea	Telecommunication and MVNO service		100.0		85.9
	SK Communications Co., Ltd.(*3)	Korea	Internet website services		100.0		64.5
	SK Broadband Co., Ltd	Korea	Telecommunication services		100.0		100.0
	PS&Marketing Corporation	Korea	Communications device retail business		100.0		100.0
	SERVICEACE Co., Ltd.	Korea	Customer center management service		100.0		100.0
	SERVICE TOP Co., Ltd.	Korea	Customer center management service		100.0		100.0
	Network O&S Co., Ltd.	Korea	Base station maintenance service		100.0		100.0
	SK Planet Co., Ltd.	Korea	Telecommunication service		98.1		98.1
	IRIVER LIMITED(*4, 5)	Korea	Manufacturing digital audio players and other portable media devices.		45.9		48.9
	SK Telecom China Holdings Co., Ltd.	China	Investment		100.0		100.0
	SK Global Healthcare Business Group, Ltd.	Hong Kong	Investment		100.0		100.0
	SKT Vietnam PTE. Ltd.	Singapore	Telecommunication service		73.3		73.3
	SKT Americas, Inc.	USA	Information gathering and consulting		100.0		100.0
	YTK Investment Ltd.	Cayman Islands	Investment association		100.0		100.0
	Atlas Investment	Cayman Islands	Investment association		100.0		100.0
	Entrix Co., Ltd.(*6)	Korea	Cloud streaming services		—		100.0
	SK techx Co., Ltd.	Korea	System software development and supply		100.0		100.0
	One Store Co., Ltd.	Korea	Telecommunication services		65.5		65.5
Subsidiaries owned by SK Planet Co., Ltd.	SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)	Korea	Data base and internet website service		100.0		100.0
	SK Planet Japan, K. K.(*5)	Japan	Digital contents sourcing service		79.5		100.0
	SK Planet Global PTE. Ltd.	Singapore	Digital contents sourcing service		100.0		100.0
	SKP GLOBAL HOLDINGS PTE. LTD.	Singapore	Investment		100.0		100.0
	SKP America LLC.	USA	Digital contents sourcing service		100.0		100.0
	shopkick Management Company, Inc.	USA	Investment		100.0		100.0
	shopkick, Inc.	USA	Reward points-based in-store shopping app development		100.0		100.0
	Planet11 E-commerce Solutions India Pvt. Ltd.(*6)	India	Electronic commerce platform service		—		99.0
	11street (Thailand) Co., Ltd.	Thailand	Electronic commerce		100.0		100.0
	Hello Nature Ltd.	Korea	Retail of agro-fisheries and livestock		100.0		100.0
Subsidiaries owned by IRIVER LIMITED	iriver Enterprise Ltd.	Hong Kong	Management of Chinese subsidiary		100.0		100.0
	iriver Inc.	USA	Marketing and sales in North America		100.0		100.0
	iriver China Co., Ltd.	China	Sales and manufacturing MP3,4 in China		100.0		100.0
	Dongguan iriver Electronics Co., Ltd.	China	Sales and manufacturing e-book in China		100.0		100.0
	groovers JP Ltd.	Japan	Digital music contents sourcing and distribution service		100.0		100.0
	S.M. LIFE DESIGN COMPANY JAPAN INC.(*6)	Japan	Selling of goods in Japan		100.0		—
	S.M. Mobile Communications JAPAN Inc.(*6)	Japan	Digital contents service		100.0		—
Subsidiaries owned by SK Telink Co., Ltd.	NSOK Co., Ltd. (formerly, Neosnetworks Co., Ltd.)(*7)	Korea	Guarding of facilities		100.0		100.0
Subsidiaries owned by SK techx Co., Ltd.	K-net Culture and Contents Venture Fund	Korea	Capital investing in startups		59.0		59.0
Subsidiaries owned by SK Broadband Co., Ltd.	Home & Service Co., Ltd.(*6)	Korea	Operation of information and communication facility		100.0		—
	SK stoa Co., Ltd.(*6)	Korea	Other telecommunication retail business		100.0		—
Others(*8)	SK Telecom Innovation Fund, L.P.	USA	Investment		100.0		100.0
	SK Telecom China Fund I L.P.	Cayman Islands	Investment		100.0		100.0
	Stonebridge Cinema Fund(*6)	Korea	Capital investing in startups		—		60.0

(*1) The ownership interest represents direct ownership interest in subsidiaries either by the Parent Company or subsidiaries of the Parent Company.

(*2) On September 28, 2017, the board of directors of the Parent Company resolved to acquire the shares of SK Telink Co., Ltd. held by the non-controlling shareholders of SK Telink Co., Ltd. on December 14, 2017 at ￦270,583 per share in cash. The Parent Company paid ￦35,281 million in cash, in aggregate, and wholly owns SK Telink Co., Ltd. as of December 31, 2017.

(*3) On November 24, 2016, the board of directors of the Parent Company resolved to acquire all of the shares of SK Communications Co., Ltd. held by the non-controlling shareholders of SK Communications Co., Ltd. on February 7, 2017 at ￦2,814 per share in cash. The Parent Company paid ￦41,550 million in cash ,in aggregate, and wholly owns SK Communications Co., Ltd. as of December 31, 2017.

(*4) Although the Group has less than 50% of the voting rights of IRIVER LIMITED, the Group is considered to have control over IRIVER LIMITED since the Group holds significantly more voting rights than any other vote holder or organized group of vote holders, and the other shareholdings are widely dispersed.

(*5) The ownership interest changed due to the non-proportional capital increase during the year ended December 31, 2017.

(*6) Details of changes in consolidation scope for the year ended December 31, 2017 are presented in Note 1-(4).

(*7) During the year ended December 31, 2017, Neosnetworks Co., Ltd. changed its name to NSOK Co., Ltd.

(*8) Others are owned together by Atlas Investment and one other subsidiary of the Parent Company.

(3)    Condensed financial information of subsidiaries

Condensed financial information of the significant subsidiaries as of and for the year ended December 31, 2017 is as follows:

(In millions of won)	As of December 31, 2017						2017
Subsidiary	Total assets		Total liabilities		Total equity		Revenue		Profit (loss)
SK Telink Co., Ltd.	￦	455,685		104,727		350,958		389,944		32,728
SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)		113,515		62,795		50,720		193,256		1,249
SK Communications Co., Ltd.		90,923		28,410		62,513		47,546		(35,454	)
SK Broadband Co., Ltd.		3,802,349		2,616,317		1,186,032		3,050,083		32,030
K-net Culture and Contents Venture Fund		250,747		35,900		214,847		—		196,250
PS&Marketing Corporation		506,883		288,881		218,002		1,766,142		391
SERVICEACE Co., Ltd.		77,681		45,501		32,180		197,408		2,599
SERVICE TOP Co., Ltd.		65,406		41,860		23,546		186,117		3,309
Network O&S Co., Ltd.		87,000		45,248		41,752		255,841		6,283
SK Planet Co., Ltd.		1,534,866		920,677		614,189		1,082,685		(513,667	)
IRIVER LIMITED(*)		130,878		17,204		113,674		69,452		(14,092	)
SKP America LLC.		412,251		—		412,251		—		(57	)
SK techx Co., Ltd.		237,700		41,561		196,139		195,948		26,827
One Store Co., Ltd.		104,891		39,874		65,017		115,596		(27,254	)
Home & Service Co., Ltd.		83,698		38,350		45,348		141,739		11
shopkick Management Company, Inc.		338,650		—		338,650		—		(238	)
shopkick, Inc.		37,336		32,219		5,117		48,836		(25,249	)

(*) The condensed financial information of IRIVER LIMITED is consolidated financial information including iriver Enterprise Ltd. and six other subsidiaries of IRIVER LIMITED. Information for the other subsidiaries in the above summary is based on their separate financial statements.

Condensed financial information of the significant subsidiaries as of and for the year ended December 31, 2016 is as follows:

(In millions of won)	As of December 31, 2016						2016
Subsidiary	Total assets		Total liabilities		Total equity		Revenue		Profit (loss)
SK Telink Co., Ltd.	￦	440,956		122,741		318,215		406,930		61,585
SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)		107,768		56,596		51,172		173,816		4,958
SK Communications Co., Ltd.		128,233		31,592		96,641		58,154		(20,411	)
SK Broadband Co., Ltd.		3,523,494		2,376,429		1,147,065		2,942,976		21,526
PS&Marketing Corporation		546,803		328,846		217,957		1,679,735		11,908
SERVICEACE Co., Ltd.		67,735		40,014		27,721		199,828		3,605
SERVICE TOP Co., Ltd.		59,004		39,121		19,883		186,740		3,971
Network O&S Co., Ltd.		69,774		35,798		33,976		218,917		3,755
SK Planet Co., Ltd.(*1)		1,935,663		834,151		1,101,512		1,177,323		(30,959	)
IRIVER LIMITED(*2)		50,075		11,941		38,134		52,328		(9,987	)
SKP America LLC.		439,209		—		439,209		—		1,226
SK techx Co., Ltd.		212,819		52,563		160,256		193,396		28,213
One Store Co., Ltd.		134,207		41,738		92,469		106,809		(22,161	)
shopkick Management Company, Inc.		354,627		—		354,627		—		(85	)
shopkick, Inc.		37,947		34,024		3,923		45,876		(27,149	)

(*1) The separate financial information of SK Planet Co., Ltd. includes pre-merger income and expenses of Commerce Planet Co., Ltd. prior to the merger date of February 1, 2016.

(*2) The condensed financial information of IRIVER LIMITED is consolidated financial information including iriver Enterprise Ltd. and five other subsidiaries of IRIVER LIMITED.

Condensed financial information of the significant subsidiaries as of and for the year ended December 31, 2015 is as follows:

(In millions of won)	As of December 31, 2015							2015
Subsidiary	Total assets		Total liabilities		Total equity			Revenue		Profit (loss)
SK Telink Co., Ltd.	￦	309,955		113,878		196,077			431,368		55,781
SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)		89,452		42,414		47,038			143,255		5,549
SK Communications Co., Ltd.		152,496		35,014		117,482			80,147		(14,826	)
SK Broadband Co., Ltd.		3,291,707		2,170,484		1,121,223			2,731,344		10,832
PS&Marketing Corporation		509,580		300,364		209,216			1,791,944		4,835
SERVICEACE Co., Ltd.		65,424		34,240		31,184			206,338		2,778
SERVICE TOP Co., Ltd.		61,897		38,482		23,415			197,092		4,396
Network O&S Co., Ltd.		77,426		48,069		29,357			210,676		6,466
SK Planet Co., Ltd.		2,406,988		784,631		1,622,357			1,624,630		(75,111	)
IRIVER LIMITED(*)		60,434		12,377		48,057			55,637		635
SKP America LLC.		380,141		—		380,141			—		791
Entrix Co., Ltd.		30,876		3,186		27,690			4,895		(1,826	)
shopkick Management Company, Inc.		306,248		7		306,241			7		(2,455	)
shopkick, Inc.		25,388		32,243		(6,855	)		33,851		(52,390	)

(*) The condensed financial information of IRIVER LIMITED is consolidated financial information including iriver Enterprise Ltd. and five other subsidiaries of IRIVER LIMITED.

(4)    Changes in subsidiaries

The list of subsidiaries that were newly included in consolidation during the year ended December 31, 2017 is as follows:

Subsidiary	Reason
S.M. LIFE DESIGN COMPANY JAPAN INC. (Refer to Note10)	Acquired by IRIVER LIMITED
S.M. Mobile Communications JAPAN Inc. (Refer to Note10)	Acquired by IRIVER LIMITED
Home & Service Co., Ltd.	Established by SK Boradband Co., Ltd.
SK stoa Co., Ltd.	Established by SK Boradband Co., Ltd.

The list of subsidiaries that were excluded from consolidation during the year ended December 31, 2017 is as follows:

Subsidiary	Reason
Entrix Co., Ltd.	Merged into SK techx Co., Ltd. during the year ended December 31, 2017.
Planet11 E-commerce Solutions India Pvt. Ltd.	Disposed during the year ended December 31, 2017.
Stonebridge Cinema Fund	Liquidated during the year ended December 31, 2017.

(5)    The information of significant non-controlling interests of the Group as of and for the years ended December 31, 2017, 2016 and 2015 are as follows. There were no dividends paid during the years ended December 31, 2017, 2016 and 2015 by subsidiaries of which non-controlling interests are significant.

(In millions of won)
	K-net Culture and Contents Venture Fund			IRIVER LIMITED			One Store Co., Ltd.
Ownership of non-controlling interests (%)		41.00			54.10			34.46
	As of December 31, 2017
Current assets	￦	625			74,873			76,810
Non-current assets		250,122			56,005			28,081
Current liabilities		(35,900	)		(9,563	)		(38,547	)
Non-current liabilities		—			(7,641	)		(1,327	)
Net assets		214,847			113,674			65,017
Carrying amount of non-controlling interests		88,087			63,382			22,405
	2017
Revenue	￦	—			69,452			115,596
Profit (loss) for the year		196,250			(14,092	)		(27,254	)
Total comprehensive profit (loss)		201,693			(14,278	)		(27,452	)
Profit (loss) attributable to non-controlling interests		80,463			(7,438	)		(9,392	)
Net cash provided by (used in) operating activities	￦	(7	)		(7,553	)		13,912
Net cash used in investing activities		(600	)		(45,002	)		(2,000	)
Net cash provided by (used in) financing activities		—			64,571			(7	)
Net increase (decrease) in cash and cash equivalents		(607	)		12,016			11,905

(In millions of won)
	SK Communications Co., Ltd.			One Store Co., Ltd.
Ownership of non-controlling interests (%)		35.46			34.46
	As of December 31, 2016
Current assets	￦	81,806			90,414
Non-current assets		46,427			43,793
Current liabilities		(30,098	)		(40,969	)
Non-current liabilities		(1,494	)		(769	)
Net assets		96,641			92,469
Carrying amount of non-controlling interests		34,265			31,863
	2016
Revenue	￦	58,154			106,809
Loss for the year		20,411			22,161
Total comprehensive loss		20,841			22,402
Loss attributable to non-controlling interests		7,240			6,772
Net cash used in operating activities	￦	(4,891	)		(4,447	)
Net cash provided by (used in) investing activities		3,625			(20,796	)
Net cash provided by financing activities		—			51,426
Net increase(decrease) in cash and cash equivalents		(1,266	)		26,183

(In millions of won)
	SK Communications Co., Ltd.
Ownership of non-controlling interests (%)		35.46
	As of December 31, 2015
Current assets	￦	95,662
Non-current assets		56,834
Current liabilities		(33,306	)
Non-current liabilities		(1,708	)
Net assets		117,482
Carrying amount of non-controlling interests		41,659
	2015
Revenue	￦	80,147
Loss for the period		14,826
Total comprehensive loss		16,698
Loss attributable to non-controlling interests		5,254
Net cash used in operating activities	￦	(2,706	)
Net cash provided by investing activities		8,723
Net cash provided by financing activities		—
Net increase in cash and cash equivalents		6,017

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Basis of Presentation

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Basis of Presentation

2. Basis of Presentation

(1)    Statement of compliance

These consolidated financial statements were prepared in accordance with International Financial Reporting Standards (“IFRS”), as issued by the International Accounting Standards Board (“IASB”).

The consolidated financial statements were authorized for issuance by the Board of Directors on February 2, 2018.

(2)    Basis of measurement

The consolidated financial statements have been prepared on the historical cost basis, except for the following material items in the consolidated statement of financial position:

• derivative financial instruments measured at fair value;

• financial instruments at fair value through profit or loss measured at fair value;

• available-for-sale financial assets measured at fair value; and

• liabilities(assets) for defined benefit plans recognized at the net of the total present value of defined benefit obligations less the fair value of plan assets.

(3)    Functional and presentation currency

Financial statements of Group entities within the Group are prepared in functional currency of each group entity, which is the currency of the primary economic environment in which each entity operates. Consolidated financial statements of the Group are presented in Korean won, which is the Parent Company’s functional and presentation currency.

(4)    Use of estimates and judgments

The preparation of the consolidated financial statements in conformity with IFRS requires management to make judgments, estimates and assumptions that affect the application of accounting policies and the reported amounts of assets, liabilities, income and expenses. Actual results may differ from these estimates.

Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period prospectively.

1)    Critical judgments

Information about critical judgments in applying accounting policies that have the most significant effect on the amounts recognized in the consolidated financial statements is included in Note 4 for the following areas: consolidation: whether the Group has de facto control over an investee, and classification of lease.

2)    Assumptions and estimation uncertainties

Information about assumptions and estimation uncertainties that have a significant risk of resulting in a material adjustment within the next financial year are included in the following notes: allowance for doubtful accounts, estimated useful lives of property and equipment and intangible assets, impairment of goodwill, recognition of provision, measurement of defined benefit liabilities, and recognition of deferred tax assets (liabilities).

3)    Fair value measurement

A number of the Group’s accounting policies and disclosures require the measurement of fair values, for both financial and non-financial assets and liabilities. The Group has established policies and processes with respect to the measurement of fair values. This includes a valuation team that has overall responsibility for overseeing all significant fair value measurements, including Level 3 fair values, and reports directly to the finance executives.

The valuation team regularly reviews significant unobservable inputs and valuation adjustments. If third party information, such as broker quotes or pricing services, is used to measure fair values, then the valuation team assesses the evidence obtained from the third parties to support the conclusion that such valuations meet the requirements of IFRS, including the level in the fair value hierarchy in which such valuations should be classified.

When measuring the fair value of an asset or a liability, the Group uses market observable data as far as possible. Fair values are categorized into different levels in a fair value hierarchy based on the inputs used in the valuation techniques as follows.

• Level 1: quoted prices (unadjusted) in active markets for identical assets or liabilities;

• Level 2: inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly (i.e. as prices) or indirectly (i.e. derived from prices); and

• Level 3: inputs for the asset or liability that are not based on observable market data (unobservable inputs).

If the inputs used to measure the fair value of an asset or a liability fall into different levels of the fair value hierarchy, then the fair value measurement is categorized in its entirety in the same level of the fair value hierarchy as the lowest level input that is significant to the entire measurement. The Group recognizes transfers between levels of the fair value hierarchy at the end of the reporting period during which the change has occurred.

Information about assumptions used for fair value measurements are included in Note 35.

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Changes in accounting policies

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Changes in accounting policies

3. Changes in accounting policies

Except the following amendments to the standards that are effective for annual periods beginning on January 1, 2017, the accounting policies have been applied consistently to all periods presented in these consolidated financial statements.

(1)    International Accounting Standards (“IAS”) 7, Cash Flow Statements

The Group adopted the amendments to IAS 7, which form a part of the IASB’s broader disclosure in the period beginning on January 1, 2017. The amendment requires the Group to provide disclosures that enable users of financial statements to evaluate changes in liabilities arising from financing activities, including both changes arising from cash flows and non-cash changes. The Group disclosed the reconciliation of the opening and closing balances of liabilities arising from financing activities including changes from financing cash flows; changes arising from obtaining or losing control of subsidiaries or other businesses; the effect of changes in foreign exchange rates; changes in fair values; and other changes in Note 38.

(2)    IAS 12, Income Taxes

The Group adopted the amendments to IAS 12 in the period beginning January 1, 2017. The amendments clarify the necessity to consider whether there are restrictions on tax laws on the sources of taxable profits which may be used for the reversal of deductible temporary difference. In addition, the amendments provide the guidance on how to estimate the probable future taxable profit and specify the circumstances where an asset can be recovered for more than its carrying amount. These amendments have no impact on the Group’s consolidated financial statements.

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Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Significant Accounting Policies

4. Significant Accounting Policies

The significant accounting policies applied by the Group in the preparation of its consolidated financial statements in accordance with IFRS are included below. The accounting policies set out below have been applied consistently to all periods presented in these consolidated financial statements.

(1)    Operating segments

An operating segment is a component of the Group that engages in business activities from which it may earn revenues and incur expenses, including revenues and expenses that relate to transactions with any of the Group’s other components. The Group’s operating segments have been determined to be each business unit, for which the Group generates separately identifiable financial information that is regularly reported to the chief operating decision maker for the purpose of resource allocation and assessment of segment performance. The Group has four reportable segments which consist of cellular services, fixed-line telecommunication services, e-commerce services and others, as described in Note 5. Segment results that are reported to the chief operating decision maker include items directly attributable to a segment as well as those that can be allocated on a reasonable basis.

The Group’s chief operating decision maker receives and reviews operating income based on Korean IFRS as the measure of segment profit and loss for each operating segment. Segment operating income differs from consolidated operating income used in the Group’s consolidated statements of income. Segment operating profit does not include certain items such as fee revenues, gain/loss from disposal of property, plant, equipment and intangible assets, impairment losses on property, plant, equipment and intangible assets, donations, bad debt expense and penalties. The chief operating decision maker does not receive any information about segment assets and liabilities.

(2)    Basis of consolidation

(i)    Business combination

A business combination is accounted for by applying the acquisition method, unless it is a combination involving entities or businesses under common control.

Consideration transferred is generally measured at fair value, identical to the measurement of identifiable net assets acquired at fair value. The difference between the acquired company’s fair value and the consideration transferred is accounted for goodwill. Any goodwill that arises is tested annually for impairment. Any gain on a bargain purchase is recognized in profit or loss immediately. Acquisition-related costs are expensed in the periods in which the costs are incurred and the services are received excluding costs to issue debt or equity securities recognized based on IAS 32 and 39.

Consideration transferred does not include the amount settled in relation to the pre-existing relationship and the amount settled in relation to the pre-existing relationship is generally recognized through profit or loss.

Contingent consideration is measured at fair value at the acquisition date. Contingent consideration classified as equity is not remeasured and its subsequent settlement is accounted for within equity. If contingent consideration is not classified as equity, the Group subsequently recognizes changes in fair value of contingent consideration through profit or loss.

(ii)    Non-controlling interests

Non-controlling interests are measured at their proportionate share of the acquiree’s identifiable net assets at the date of acquisition.

Changes in a Controlling Company’s ownership interest in a subsidiary that do not result in the Controlling Company losing control of the subsidiary are accounted for as equity transactions.

(iii)    Subsidiaries

Subsidiaries are entities controlled by the Group. The Group controls an investee when it is exposed, or has rights, to variable returns from its involvement with the investee and has the ability to affect those returns through its power over the investee. Consolidation of an investee begins from the date the Group obtains control of the investee and cease when the Group loses control of the investee.

(iv)    Loss of control

If the Group loses control of a subsidiary, the Group derecognizes the assets and liabilities of the former subsidiary from the consolidated statement of financial position and recognizes gain or loss associated with the loss of control attributable to the former controlling interest. Any investment retained in the former subsidiary is recognized at its fair value when control is lost.

(v)    Interest in investees accounted for using the equity method

Interest in investees accounted for using the equity method composed of interest in associates and joint ventures. An associate is an entity in which the Group has significant influence, but not control, over the entity’s financial and operating policies. A joint venture is a joint arrangement whereby the Group that has joint control of the arrangement has rights to the net assets of the arrangement.

The investment in an associate and a joint venture is initially recognized at cost including transaction costs and the carrying amount is increased or decreased to recognize the Group’s share of the profit or loss and changes in equity of the associate or the joint venture after the date of acquisition.

(vi)    Intra-group transactions

Intra-group balances and transactions, and any unrealized income and expenses arising from intra-group transactions, are eliminated in preparing the consolidated financial statements. The Group’s share of unrealized gain incurred from transactions with investees accounted for using the equity method are eliminated and unrealized loss are eliminated using the same basis if there are no evidence of asset impairments.

(vii)    Business combinations under common control

SK Holdings Co., Ltd. is the ultimate controlling entity of the Group. The assets and liabilities acquired under business combination under common control are recognized at the carrying amounts in the ultimate controlling shareholder’s consolidated financial statements. The difference between consideration and carrying amount of net assets acquired is added to or subtracted from capital surplus and others.

(3)    Cash and cash equivalents

Cash and cash equivalents comprise cash balances, call deposits and financial assets with maturities of three months or less from the acquisition date that are easily convertible to cash and subject to an insignificant risk of changes in their fair value.

(4)    Inventories

Inventories are stated at the acquisition cost using the average method. During the period, a perpetual inventory system is used to track inventory quantities, which is adjusted to the physical inventory counts performed at the period end. When the net realizable value of inventories is less than the acquisition cost, the carrying amount is reduced to the net realizable value and any difference is charged to current operations as operating expenses.

(5)    Non-derivative financial assets

The Group recognizes and measures non-derivative financial assets by the following four categories: financial assets at fair value through profit or loss, held-to-maturity investments, loans and receivables and available-for-sale financial assets. The Group recognizes financial assets in the consolidated statement of financial position when the Group becomes a party to the contractual provisions of the instrument.

Upon initial recognition, non-derivative financial assets not at fair value through profit or loss are measured at their fair value plus transaction costs that are directly attributable to the acquisition of the asset.

(i)    Financial assets at fair value through profit or loss

A financial asset is classified as financial asset at fair value through profit or loss if it is held for trading or is designated as such upon initial recognition. Upon initial recognition, transaction costs are recognized in profit or loss when incurred. Financial assets at fair value through profit or loss are measured at fair value, and changes therein are recognized in profit or loss.

(ii)    Held-to-maturity investments

A non-derivative financial asset with a fixed or determinable payment and fixed maturity, for which the Group has the positive intention and ability to hold to maturity, are classified as held-to-maturity investment. Subsequent to initial recognition, held-to-maturity investments are measured at amortized cost using the effective interest rate method.

(iii)    Loans and receivables

Loans and receivables are financial assets with fixed or determinable payments that are not quoted in an active market. Subsequent to initial recognition, loans and receivables are measured at amortized cost using the effective interest method except for loans and receivables of which the effect of discounting is immaterial.

(iv)    Available-for-sale financial assets

Available-for-sale financial assets are those non-derivative financial assets that are designated as available-for-sale or are not classified as financial assets at fair value through profit or loss, held-to-maturity investments or loans and receivables. Subsequent to initial recognition, they are measured at fair value with changes in fair value, net of any tax effect, recorded in other comprehensive income (OCI) in equity. Investments in equity instruments that do not have a quoted market price in an active market and whose fair value cannot be reliably measured are measured at cost.

(v)    De-recognition of financial assets

The Group derecognizes a financial asset when the contractual rights to the cash flows from the asset expire, or it transfers the rights to receive the contractual cash flows on the financial asset in a transaction in which substantially all the risks and rewards of ownership of the financial asset are transferred. Any interest in transferred financial assets that is created or retained by the Group is recognized as a separate asset or liability. If the Group retains substantially all the risks and rewards of ownership of the transferred financial assets, the Group continues to recognize the transferred financial assets and recognizes financial liabilities for the consideration received.

(vi)    Offsetting between financial assets and financial liabilities

Financial assets and liabilities are offset and the net amount is presented in the consolidated statement of financial position only when the Group currently has a legally enforceable right to offset the recognized amounts, and there is the intention to settle on a net basis or to realize the asset and settle the liability simultaneously.

(6)    Derivative financial instruments, including hedge accounting

Derivatives are initially recognized at fair value. Subsequent to initial recognition, derivatives are measured at fair value, and changes therein are accounted for as described below.

(i)    Hedge accounting

The Group holds forward exchange contracts, interest rate swaps, currency swaps and other derivative contracts to manage interest rate risk and foreign exchange risk. The Group designates derivatives as hedging instruments to hedge the risk of changes in the fair value of assets, liabilities or firm commitments (a fair value hedge) and foreign currency risk of highly probable forecasted transactions or firm commitments (a cash flow hedge).

On initial designation of the hedge, the Group formally documents the relationship between the hedging instrument(s) and hedged item(s), including the risk management objectives and strategy in undertaking the hedge transaction, together with the methods that will be used to assess the effectiveness of the hedging relationship.

Fair value hedge

Changes in the fair value of a derivative hedging instrument designated as a fair value hedge are recognized in profit or loss. The gain or loss from remeasuring the hedging instrument at fair value for a derivative hedging instrument and the gain or loss on the hedged item attributable to the hedged risk are recognized in profit or loss in the same line item of the consolidated statement of income.

The Group discontinues fair value hedge accounting if the hedging instrument expires or is sold, terminated or exercised, or if the hedge no longer meets the criteria for hedge accounting. Any adjustment arising from gain or loss on the hedged item attributable to the hedged risk is amortized to profit or loss from the date the hedge accounting is discontinued.

Cash flow hedge

When a derivative is designated to hedge the variability in cash flows attributable to a particular risk associated with a recognized asset or liability or a highly probable forecasted transaction that could affect profit or loss, the effective portion of changes in the fair value of the derivative is recognized in other comprehensive income, net of tax, and presented in the hedging reserve in equity. Any ineffective portion of changes in the fair value of the derivative is recognized immediately in profit or loss. If the hedging instrument no longer meets the criteria for hedge accounting, expires or is sold, terminated, exercised, or the designation is revoked, then hedge accounting is discontinued prospectively. The cumulative gain or loss on the hedging instrument that has been recognized in other comprehensive income is reclassified to profit or loss in the periods during which the forecasted transaction occurs. If the forecasted transaction is no longer expected to occur, then the balance in other comprehensive income is recognized immediately in profit or loss.

(ii)    Separable embedded derivatives

Embedded derivatives are separated from the host contract and accounted for separately only if the following criteria have been met:

(a) the economic characteristics and risks of the embedded derivative are not closely related to those of the host contract;

(b) a separate instrument with the same terms as the embedded derivative would meet the definition of a derivative; and

(c) the hybrid (combined) instrument is not measured at fair value with changes in fair value recognized in profit or loss.

Changes in the fair value of separable embedded derivatives are recognized immediately in profit or loss.

(iii)    Other derivative financial instruments

Changes in the fair value of other derivative financial instrument not designated as a hedging instrument are recognized immediately in profit or loss.

(7)    Impairment of financial assets

A financial asset not carried at fair value through profit or loss is assessed at each reporting date to determine whether there is objective evidence that it is impaired. A financial asset is impaired if objective evidence indicates that a loss event has occurred after the initial recognition of the asset, and that the loss event had a negative effect on the estimated future cash flows of that asset that can be estimated reliably. However, losses expected as a result of future events, regardless of likelihood, are not recognized.

Objective evidence that a financial asset is impaired includes following loss events:

• significant financial difficulty of the issuer or obligor;

• a breach of contract, such as default or delinquency in interest or principal payments;

• the lender, for economic or legal reasons relating to the borrower’s financial difficulty, granting to the borrower a concession that the lender would not otherwise consider;

• it becoming probable that the borrower will enter bankruptcy or other financial reorganization;

• the disappearance of an active market for that financial asset because of financial difficulties; or

• observable data indicating that there is a measurable decrease in the estimated future cash flows from a group of financial assets since the initial recognition of those assets, although the decrease cannot yet be identified with the individual financial assets in the group.

In addition, for an investment in an equity security, a significant or prolonged decline in its fair value below its cost is objective evidence of impairment.

If financial assets have objective evidence that they are impaired, impairment losses are measured and recognized.

(i)    Financial assets measured at amortized cost

An impairment loss in respect of a financial asset measured at amortized cost is calculated as the difference between its carrying amount and the present value of its estimated future cash flows discounted at the asset’s original effective interest rate. The Group can recognize impairment losses directly or by establishing an allowance account. If, in a subsequent period, the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized (such as an improvement in the debtor’s credit rating), the previously recognized impairment loss is reversed either directly or by adjusting an allowance account.

(ii)    Financial assets carried at cost

If there is objective evidence that an impairment loss has occurred on an unquoted equity instrument that is not carried at fair value because its fair value cannot be reliably measured, or on a derivative asset that is linked to and must be settled by delivery of such an unquoted equity instrument, the amount of the impairment loss is measured as the difference between the carrying amount of the financial asset and the present value of estimated future cash flows discounted at the current market rate of return for a similar financial asset. Such impairment losses are not reversed.

(iii)    Available-for-sale financial assets

When a decline in the fair value of an available-for-sale financial asset has been recognized in other comprehensive income and there is objective evidence that the asset is impaired, the cumulative loss that had been recognized in other comprehensive income is reclassified from equity to profit or loss as a reclassification adjustment even though the financial asset has not been derecognized. Impairment losses recognized in profit or loss for an investment in an equity instrument classified as available-for-sale is not reversed through profit or loss subsequently. If, in a subsequent period, the fair value of a debt instrument classified as available-for-sale increases and the increase can be objectively related to an event occurring after the impairment loss was recognized in profit or loss, the impairment loss is reversed, with the amount of the reversal recognized in profit or loss.

(8)    Property and equipment

Property and equipment are initially measured at cost. The cost of property and equipment includes expenditures arising directly from the construction or acquisition of the asset, any costs directly attributable to bringing the asset to the location and condition necessary for it to be capable of operating in the manner intended by management and the initial estimate of the costs of dismantling and removing the item and restoring the site on which it is located.

Subsequent to initial recognition, an item of property and equipment is carried at its cost less any accumulated depreciation and any accumulated impairment losses.

Subsequent costs are recognized in the carrying amount of property and equipment at cost or, if appropriate, as a separate item if it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day servicing are recognized in profit or loss as incurred.

Property and equipment, except for land, are depreciated on a straight-line basis over estimated useful lives that appropriately reflect the pattern in which the asset’s future economic benefits are expected to be consumed. A component that is significant compared to the total cost of property and equipment is depreciated over its separate useful life.

Gains and losses on disposal of an item of property and equipment are determined by comparing the proceeds from disposal with the carrying amount of property and equipment and are recognized as other non-operating income (loss).

The estimated useful lives of the Group’s property and equipment are as follows:

	Useful lives (years)
Buildings and structures		15 ~ 40
Machinery		3 ~ 15
Other property and equipment		2 ~ 10

Depreciation methods, useful lives and residual values are reviewed at the end of each reporting date and adjusted, if appropriate. The change is accounted for as a change in an accounting estimate.

(9)    Borrowing costs

The Group capitalizes borrowing costs directly attributable to the acquisition, construction or production of a qualifying asset as part of the cost of that asset. Other borrowing costs are recognized in expense as incurred. A qualifying asset is an asset that requires a substantial period of time to get ready for its intended use or sale. Financial assets are not qualifying assets. Assets that are ready for their intended use or sale when acquired are not qualifying assets.

To the extent that the Group borrows funds specifically for the purpose of obtaining a qualifying asset, the Group determines the amount of borrowing costs eligible for capitalization as the actual borrowing costs incurred on that borrowing during the period less any investment income on the temporary investment of those borrowings. To the extent that the Group borrows funds generally and uses them for the purpose of obtaining a qualifying asset, the Group determines the amount of borrowing costs eligible for capitalization by applying a capitalization rate to the expenditures on that asset. The capitalization rate is the weighted average of the borrowing costs applicable to the borrowings of the Group that are outstanding during the period, other than borrowings made specifically for the purpose of obtaining a qualifying asset. The amount of borrowing costs that the Group capitalizes during a period do not exceed the amount of borrowing costs incurred during that period.

(10)    Intangible assets

Intangible assets are measured initially at cost and, subsequently, are carried at cost less accumulated amortization and accumulated impairment losses.

Amortization of intangible assets except for goodwill is calculated on a straight-line basis over the estimated useful lives of intangible assets from the date that they are available for use. The residual value of intangible assets is zero. However, club memberships are expected to be available for use as there are no foreseeable limits to the periods. This intangible asset is determined as having indefinite useful lives and not amortized.

The estimated useful lives of the Group’s intangible assets are as follows:

	Useful lives (years)
Frequency usage rights	5 ~ 13
Land usage rights	5
Industrial rights	5, 10
Development costs	3 ~ 5
Facility usage rights	10, 20
Customer relations	3 ~ 7
Other	3 ~ 20

Amortization periods and the amortization methods for intangible assets with finite useful lives are reviewed at the end of each reporting period. The useful lives of intangible assets that are not being amortized are reviewed at the end of each reporting period to determine whether events and circumstances continue to support indefinite useful life assessments for those assets. Changes are accounted for as changes in accounting estimates.

Expenditures on research activities are recognized in profit or loss as incurred. Development expenditures are capitalized only if development costs can be measured reliably, the product or process is technically and commercially feasible, future economic benefits are probable, and the Group intends to and has sufficient resources to complete development and to use or sell the asset. Other development expenditures are recognized in profit or loss as incurred.

Subsequent expenditures are capitalized only when they increase the future economic benefits embodied in the specific asset to which it relates. All other expenditures, including expenditures on internally generated goodwill and brands, are recognized in profit or loss as incurred.

(11)    Government grants

Government grants are not recognized unless there is reasonable assurance that the Group will comply with the grant’s conditions and that the grant will be received.

(i)    Grants related to assets

Government grants whose primary condition is that the Group purchases, constructs or otherwise acquires a long-term asset are deducted in calculating the carrying amount of the asset. The grant is recognized in profit or loss over the life of a depreciable asset as a reduction to depreciation expense.

(ii)    Grants related to income

Government grants which are intended to compensate the Group for expenses incurred are deducted from the related expenses.

(12)    Investment property

Property held for the purpose of earning rentals or benefiting from capital appreciation is classified as investment property. Investment property is initially measured at its cost. Transaction costs are included in the initial measurement. Subsequently, investment property is carried at depreciated cost less any accumulated impairment losses.

Subsequent costs are recognized in the carrying amount of investment property at cost or, if appropriate, as a separate item if it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day servicing are recognized in profit or loss as incurred.

Investment property except for land, are depreciated on a straight-line basis over 15~40 years as estimated useful lives.

Depreciation methods, useful lives and residual values are reviewed at the end of each reporting date and adjusted, if appropriate. The change is accounted for as a change in an accounting estimate.

(13)    Impairment of non-financial assets

The carrying amounts of the Group’s non-financial assets, other than assets arising from employee benefits, inventories, deferred tax assets and non-current assets held for sale, are reviewed at the end of the reporting period to determine whether there is any indication of impairment. If any such indication exists, then the asset’s recoverable amount is estimated. Goodwill and intangible assets that have indefinite useful lives or that are not yet available for use, irrespective of whether there is any indication of impairment, are tested for impairment annually by comparing their recoverable amount to their carrying amount.

The Group estimates the recoverable amount of an individual asset, if it is impossible to measure the individual recoverable amount of an asset, then the Group estimates the recoverable amount of cash-generating unit (“CGU”). A CGU is the smallest identifiable group of assets that generates cash inflows that are largely independent of the cash inflows from other assets or groups of assets. The recoverable amount of an asset or CGU is the greater of its value in use and its fair value less costs to sell. The value in use is estimated by applying a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset or CGU for which estimated future cash flows have not been adjusted, to the estimated future cash flows expected to be generated by the asset or CGU.

An impairment loss is recognized in profit or loss to the extent the carrying amount of the asset exceeds its recoverable amount.

Goodwill acquired in a business combination is allocated to each CGU that is expected to benefit from the synergies arising from the business acquired. Any impairment identified at the CGU level will first reduce the carrying value of goodwill and then be used to reduce the carrying amount of the other assets in the CGU on a pro rata basis. Except for impairment losses in respect of goodwill which are never reversed, an impairment loss is reversed if there has been a change in the estimates used to determine the recoverable amount. An impairment loss is reversed only to the extent that the asset’s carrying amount does not exceed the carrying amount that would have been determined, net of depreciation or amortization, if no impairment loss had been recognized.

(14)    Leases

The Group classifies and accounts for leases as either a finance or operating lease, depending on the terms. Leases where the Group assumes substantially all of the risks and rewards of ownership are classified as finance leases. All other leases are classified as operating leases.

(i)    Finance leases

At the commencement of the lease term, the Group recognizes as finance assets and finance liabilities in its consolidated statement of financial position, the lower amount of the fair value of the leased property and the present value of the minimum lease payments, each determined at the inception of the lease. Any initial direct costs are added to the amount recognized as an asset.

Minimum lease payments are apportioned between the finance charge and the reduction of the outstanding liability. The finance charge is allocated to each period during the lease term so as to produce a constant periodic rate of interest on the remaining balance of the liability. Contingent rents are charged as expenses in the periods in which they are incurred.

The depreciable amount of a leased asset is allocated to each accounting period during the period of expected use on a systematic basis consistent with the depreciation policy the Group adopts for depreciable assets that are owned. If there is no reasonable certainty that the Group will obtain ownership by the end of the lease term, the asset is fully depreciated over the shorter of the lease term and its useful life. The Group reviews to determine whether the leased assets are impaired at the reporting date.

(ii)    Operating leases

Leases where the lessor retains a significant portion of the risks and rewards of ownership are classified as operating leases. Payments made under operating leases (net of any incentives received from the lessor) are recognized in profit or loss on a straight-line basis over the period of the lease.

(iii)    Determining whether an arrangement contains a lease

Determining whether an arrangement is, or contains, a lease is based on the substance of the arrangement and requires an assessment of whether fulfillment of the arrangement is dependent on the use of a specific asset and the arrangement conveys a right to use the asset.

At inception or reassessment of the arrangement, the Group separates payments and other consideration required by such an arrangement into those for the lease and those for other elements on the basis of their relative fair values. If the Group concludes for a financial lease that it is impracticable to separate the payments reliably, the Group recognizes an asset and a liability at an amount equal to the fair value of the underlying asset that was identified as the subject of the lease. Subsequently, the liability is reduced as payments are made and an imputed finance charge on the liability is recognized using the Group’s incremental borrowing rate of interest.

(15)    Non-current assets held for sale

Non-current assets, or disposal groups comprising assets and liabilities, that are expected to be recovered primarily through sale rather than through continuing use, are classified as held for sale. In order to be classified as held for sale, the asset (or disposal group) must be available for immediate sale in its present condition and its sale must be highly probable. The assets or disposal group that are classified as non-current assets held for sale are measured at the lower of their carrying amount and fair value less cost to sell. The Group recognizes an impairment loss for any initial or subsequent write-down of an asset (or disposal group) to fair value less costs to sell, and a gain for any subsequent increase in fair value less costs to sell, up to the cumulative impairment loss previously recognized in accordance with IAS 36, Impairment of Assets.

A non-current asset that is classified as held for sale or part of a disposal group classified as held for sale is not depreciated (or amortized).

(16)    Non-derivative financial liabilities

The Group classifies non-derivative financial liabilities into financial liabilities at fair value through profit or loss or other financial liabilities in accordance with the substance of the contractual arrangement. The Group recognizes financial liabilities in the consolidated statement of financial position when the Group becomes a party to the contractual provisions of the financial liability.

(i)    Financial liabilities at fair value through profit or loss

Financial liabilities at fair value through profit or loss include financial liabilities held for trading or designated as such upon initial recognition. Subsequent to initial recognition, financial liabilities at fair value through profit or loss are measured at fair value, and changes therein are recognized in profit or loss. Upon initial recognition, transaction costs that are directly attributable to the issue of the financial liability are recognized in profit or loss as incurred.

(ii)    Other financial liabilities

Non-derivative financial liabilities other than financial liabilities at fair value through profit or loss are classified as other financial liabilities. At the date of initial recognition, other financial liabilities are measured at fair value minus transaction costs that are directly attributable to the issue of the financial liability. Subsequent to initial recognition, other financial liabilities are measured at amortized cost using the effective interest method.

The Group derecognizes a financial liability from the consolidated statement of financial position when it is extinguished (i.e. when the obligation specified in the contract is discharged, cancelled or expires).

(17)    Employee benefits

(i)    Short-term employee benefits

Short-term employee benefits are employee benefits that are due to be settled within 12 months after the end of the period in which the employees render the related service. When an employee has rendered service to the Group during an accounting period, the Group recognizes the undiscounted amount of short-term employee benefits expected to be paid in exchange for that service.

(ii)    Other long-term employee benefits

Other long-term employee benefits include employee benefits that are settled beyond 12 months after the end of the period in which the employees render the related service. The Group’s net obligation in respect of long-term employee benefits is the amount of future benefit that employees have earned in return for their service in the current and prior periods. That benefit is discounted to determine its present value. Remeasurements are recognized in profit or loss in the period in which they arise.

(iii)    Retirement benefits: defined contribution plans

When an employee has rendered service to the Group during a period, the Group recognizes the contribution payable to a defined contribution plan in exchange for that service as a liability (accrued expense), after deducting any contribution already paid. If the contribution already paid exceeds the contribution due for service before the end of the reporting period, the Group recognizes that excess as an asset (prepaid expense) to the extent that the prepayment will lead to a reduction in future payments or a cash refund.

(iv)    Retirement benefits: defined benefit plans

At the end of reporting period, defined benefits liabilities relating to defined benefit plans are recognized at present value of defined benefit obligations net of fair value of plan assets.

The calculation is performed annually by an independent actuary using the projected unit credit method. When the fair value of plan assets exceeds the present value of the defined benefit obligation, the Group recognizes an asset, to the extent of the present value of any economic benefits available in the form of refunds from the plan or reduction in the future contributions to the plan.

Remeasurements of the net defined benefit liability, which comprise actuarial gains and losses, the return on plan assets (excluding interest) and the effect of the asset ceiling (if any, excluding interest), are recognized immediately in other comprehensive income. The Group determines net interests on net defined benefit liability (asset) by multiplying discount rate determined at the beginning of the annual reporting period and considers changes in net defined benefit liability (asset) from contributions and benefit payments. Net interest costs and other costs relating to the defined benefit plan are recognized through profit or loss.

When the plan amendment or curtailment occurs, gains or losses on amendment or curtailment in benefits for the past service provided are recognized through profit or loss. The Group recognizes gain or loss on a settlement when the settlement of defined benefit plan occurs.

(v)    Termination benefits

The Group recognizes a liability and expense for termination benefits at the earlier of the period when the Group can no longer withdraw the offer of those benefits and the period when the Group recognizes costs for a restructuring that involves the payment of termination benefits. If benefits are payable more than 12 months after the reporting period, they are discounted to their present value.

(18)    Provisions

Provisions are recognized when the Group has a present legal or constructive obligation as a result of a past event, it is probable that an outflow of resources embodying economic benefits will be required to settle the obligation and a reliable estimate can be made of the amount of the obligation.

The risks and uncertainties that inevitably surround many events and circumstances are taken into account in reaching the best estimate of a provision. Where the effect of the time value of money is material, provisions are determined at the present value of the expected future cash flows.

Where some or all of the expenditures required to settle a provision are expected to be reimbursed by another party, the reimbursement is recognized when, and only when, it is virtually certain that reimbursement will be received if the entity settles the obligation. The reimbursement is treated as a separate asset.

Provisions are reviewed at the end of each reporting period and adjusted to reflect the current best estimates. If it is no longer probable that an outflow of resources embodying economic benefits will be required to settle the obligation, the provision is reversed.

A provision is used only for expenditures for which the provision was originally recognized.

(19)    Transactions in foreign currencies

(i)    Foreign currency transactions

Transactions in foreign currencies are translated to the functional currency of Group at exchange rates at the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are retranslated to the functional currency using the reporting date’s exchange rate. Non-monetary assets and liabilities denominated in foreign currencies that are measured at fair value are retranslated to the functional currency at the exchange rate at the date that the fair value was determined.

Foreign currency differences arising on retranslation are recognized in profit or loss, except for differences arising on the retranslation of available-for-sale equity instruments.

(ii)    Foreign operations

If the presentation currency of the Group is different from a foreign operation’s functional currency, the financial statements of the foreign operation are translated into the presentation currency using the following methods:

The assets and liabilities of foreign operations, whose functional currency is not the currency of a hyperinflationary economy, are translated to presentation currency at exchange rates at the reporting date. The income and expenses of foreign operations are translated to functional currency at exchange rates at the dates of the transactions. Foreign currency differences are recognized in other comprehensive income.

Any goodwill arising on the acquisition of a foreign operation and any fair value adjustments to the carrying amounts of assets and liabilities arising on the acquisition of that foreign operation is treated as assets and liabilities of the foreign operation. Thus they are expressed in the functional currency of the foreign operation and translated at the closing rate at the reporting date.

When a foreign operation is disposed of, the relevant amount in the translation is transferred to profit or loss as part of the profit or loss on disposal. On the partial disposal of a subsidiary that includes a foreign operation, the relevant proportion of such cumulative amount is reattributed to non-controlling interest. In any other partial disposal of a foreign operation, the relevant proportion is reclassified to profit or loss.

(20)    Share capital

Ordinary shares are classified as equity. Incremental costs directly attributable to the issuance of ordinary shares and share options are recognized as a deduction from equity, net of any tax effects.

When the Group repurchases its own shares, the amount of the consideration paid is recognized as a deduction from equity and classified as treasury shares. The profits or losses from the purchase, disposal, reissue, or retirement of treasury shares are directly recognized in equity being as transaction with owners.

(21)    Hybrid bond

The Group recognizes a financial instrument issued by the Group as an equity instrument if it does not include contractual obligation to deliver financial assets including cash to the counter party.

(22)    Share-based Payment

For equity-settled share-based payment transaction, if the fair value of the goods or services received cannot be reliably estimated, the Group measures their value indirectly by reference to the fair value of the equity instruments granted. Related expense, with a corresponding increase in capital surplus and others is recognized over the vesting period of the awards. The amount recognized as an expense is adjusted to reflect the number of awards for which the related service and non-market performance conditions are expected to be met, such that the amount ultimately recognized is based on the number of awards that meet the related service and non-market performance conditions at the vesting date.

(23)    Revenue

Revenue from the sale of goods, rendering of services or use of the Group assets is measured at the fair value of the consideration received or receivable. Returns, trade discounts and volume rebates are recognized as a reduction of revenue.

When two or more revenue generating activities or deliverables are sold under a single arrangement, each deliverable that is considered to be a separate unit of account is accounted for separately. The allocation of consideration from a revenue arrangement to its separate units of account is based on the relative fair values of each unit.

(i)    Services rendered

Revenue from cellular services consists of revenue from basic charges, voice charges, data charges, data-roaming services and interconnection charges. Such revenues are recognized as services are performed.

Revenue from fixed-line services includes domestic and long distance call charges, international phone connection charges, and broadband internet services. Such revenues are recognized as the related services are performed.

Revenue from other services rendered is recognized in profit or loss in proportion to the stage of completion of the transaction at the reporting date. The stage of completion is assessed by reference to surveys of work performed.

(ii)    Goods sold

Revenue is recognized when persuasive evidence exists, usually in the form of an executed sales agreement, that the significant risks and rewards of ownership have been transferred to the buyer, recovery of the consideration is probable, the associated costs and possible return of goods can be estimated reliably, there is no continuing management involvement with the goods, and the amount of revenue can be measured reliably.

(iii)    Commission revenue

In connection with the commission revenue from e-commerce services with following characteristics, the Group has determined that it is acting as an agent.

• The Group does not bear inventory risk or have responsibility for the delivery goods;

• All of the credit risks are borne by suppliers of goods though the Group collects the proceeds from end customers on behalf of the suppliers; and

• The Group has no latitude in establishing prices regarding goods sold in e-commerce.

(iv)    Customer loyalty programs

For customer loyalty programs, the fair value of the consideration received or receivable in respect of the initial sale is allocated between the award credits and the other components of the sale. The amount allocated to the award credits is estimated by reference to the fair value of the services to be provided with respect to the redeemable award credits. The fair value of the services to be provided with respect to the redeemable portion of the award credits granted to the customers in accordance with customer loyalty programs is estimated taking into account the expected redemption rate and timing of the expected redemption. Considerations allocated to the award credits are deferred and revenue is recognized when the award credits are recovered and the Group performs its obligation to provide the service. The amount of revenue recognized is based on the relative size of the total award credits that are expected to be redeemed and the redeemed award credits in exchange for services.

(24)    Operating profit

Operating profit is the result generated from the continuing principal revenue producing activities of the Group as well as other income and expenses related to operating activities. Operating profit excludes net finance costs, share of profit of equity accounted investees and income taxes.

(25)    Finance income and finance costs

Finance income comprises interest income on funds invested (including available-for-sale financial assets), dividend income, gains on disposal of available-for-sale financial assets, changes in fair value of financial assets at fair value through profit or loss, and gains on hedging instruments that are recognized in profit or loss. Interest income is recognized as it accrues in profit or loss, using the effective interest rate method. Dividend income is recognized in profit or loss on the date that the Group’s right to receive payment is established.

Finance costs comprise interest expense on borrowings, changes in fair value of financial assets at fair value through profit or loss, and losses on hedging instruments that are recognized in profit or loss. Interest expense on borrowings and debentures are recognized in profit or loss using the effective interest rate method.

(26)    Income taxes

Income tax expense comprises current and deferred tax. Current tax and deferred tax are recognized in profit or loss except to the extent that it relates to a business combination, or items recognized directly in equity or in other comprehensive income.

The Group pays income tax in accordance with the tax-consolidation system which applies to the Parent Company and wholly owned subsidiaries.

(i)    Current tax

In accordance with the tax-consolidation system, the Parent Company calculates current taxes for the Parent Company and its wholly owned domestic subsidiaries and recognizes the income tax payable as current tax liabilities of the Parent Company. Current tax is the expected tax payable or receivable on the taxable profit or loss for the year, using tax rates enacted or substantively enacted at the end of the reporting period and includes interests and fines related to income taxes paid or payable. The taxable profit is different from the accounting profit for the period since the taxable profit is calculated excluding the temporary differences, which will be taxable or deductible in determining taxable profit (tax loss) of future periods, and non-taxable or non-deductible items from the accounting profit.

(ii)    Deferred tax

Deferred tax is recognized, using the asset-liability method, in respect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for taxation purposes. The Group recognizes a deferred tax liability for all taxable temporary differences, except for the difference associated with investments in subsidiaries and associates that the Group is able to control the timing of the reversal of the temporary difference and it is probable that the temporary difference will not reverse in the foreseeable future. The Group recognizes a deferred tax asset for all deductible temporary differences to the extent that it is probable that the temporary difference will reverse in the foreseeable future and taxable profit will be available against which the temporary difference can be utilized.

A deferred tax asset is recognized for the carryforward of unused tax losses and unused tax credits to the extent that it is probable that future taxable profit will be available against which the unused tax losses and unused tax credits can be utilized. Future taxable profit is dependent on the reversal of taxable temporary differences. If there are insufficient taxable temporary differences to recognize the deferred tax asset, the business plan of the Group and the reversal of existing temporary differences are considered in determining the future taxable profit.

The Group reviews the carrying amount of a deferred tax asset at the end of each reporting period and reduces the carrying amount to the extent that it is no longer probable that sufficient taxable profit will be available to allow the benefit of part or all of that deferred tax asset to be utilized.

Deferred tax assets and liabilities are measured at the tax rates that are expected to apply to the period when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period. The measurement of deferred tax liabilities and deferred tax assets reflects the tax consequences that would follow from the manner in which the Group expects, at the end of the reporting period, to recover or settle the carrying amount of its assets and liabilities.

Deferred tax assets and liabilities are offset only if there is a legally enforceable right to offset the related current tax liabilities and assets, and they relate to income taxes levied by the same tax authority and they are intended to be settled current tax liabilities and assets on a net basis. Income tax expense in relation to dividend payments is recognized when liabilities relating to the dividend payments are recognized.

(27)    Earnings per share

The Group presents basic and diluted earnings per share (EPS) data for its ordinary shares. Basic EPS is calculated by dividing the profit or loss attributable to ordinary shareholders of the Parent Company by the weighted average number of ordinary shares outstanding during the period, adjusted for own shares held. Diluted EPS is determined by adjusting the profit or loss attributable to ordinary shareholders and the weighted average number of ordinary shares outstanding, adjusted for own shares held, for the effects of all dilutive potential ordinary shares, which comprise share options granted to employees, if any.

(28)    Standards issued but not yet effective

The following new standards are effective for annual periods beginning after January 1, 2017 and earlier application is permitted; however, the Group has not early adopted the following new standards in preparing these financial statements.

1)    IFRS 9, Financial Instruments

IFRS 9, published in July 2014 which will replace the IAS 39 Financial Instruments: Recognition and Measurement, is effective for annual periods beginning on or after January 1, 2018, with early adoption permitted. The Group currently plans to apply IFRS 9 in the period beginning on January 1, 2018.

IFRS 9 will be applied retrospectively with exemption allowing the Group not to restate comparative information for prior periods with respect to classification and measurement including impairment changes. The Group will recognize any difference on the measurement of financial assets and liabilities in the opening balance of retained earnings of the year beginning January 1, 2018. In the case of hedge accounting, the prospective application is allowed except for those specified in IFRS 9 such as accounting for the time value of options and the forward element of forward contracts which requires retrospective application.

Key features of IFRS 9 includes new classification and measurement approach for financial assets that reflects the business model in which assets are managed and their cash flow characteristics, impairment model based on changes in expected credit losses, and new approach to hedge qualification and methods for assessing hedge effectiveness.

To ensure smooth implementation of IFRS 9, the Group needs to assess the financial impact of adopting IFRS 9, to formulate the accounting policy, and to design, implement and enhance the accounting system and related controls. The expected quantitative impact of adopting IFRS 9 on the Group’s financial statements cannot be reliably estimated because it will be dependent on the financial instruments that the Group holds and economic conditions at that time as well as accounting elections and judgments that it will make in the future.

Based on the circumstances and information available as of December 31, 2017, the Group preliminary assessed the financial impact on its consolidated financial statements resulting from the adoption of IFRS 9. The results of the preliminary assessment are as follows. The results are subject to change according to additional information available in subsequent period.

i)    Classification and measurement of financial assets

Classification of financial assets under IFRS 9 is driven by the entity’s business model for managing financial assets and their contractual cash flows. This contains three principal classification categories: financial assets measured at amortized cost, fair value through other comprehensive income (FVOCI) and fair value through profit or loss (FVTPL). Derivatives embedded in contracts where the host is a financial asset are never bifurcated. Instead, the hybrid financial instrument as a whole is assessed for classification. Details of the classification based on business models and contractual cash flows are as follows:

	Contractual cash flow characteristics
Business model assessment(*1)	Solely payments of principal and interest	Others
Hold to collect contractual cash flows	Amortized cost(*2)	FVTPL-measured at fair value(*3)
Hold to collect contractual cash flows and sell financial assets	FVOCI- measured at fair value(*2)
Hold to sell financial assets and others	FVTPL-measured at fair value

(*1) The business model is expected to be assessed at portfolio level.

(*2) To eliminate or significantly reduce the accounting mismatch, the Group may irrevocably designate a financial asset as measured at FVTPL using the fair value option at initial recognition.

(*3) Equity instruments that are not held for trading may be irrevocably designated as FVOCI using the fair value option. This election will be made on an investment-by-investment basis.

As new classification requirements for financial assets under IFRS 9 are more stringent than requirements under IAS 39, the adoption of the new standard may result in increase in financial assets designated as FVTPL and higher volatility in profit or loss of the Group. As of December 31, 2017, the Group’s financial assets consist of ￦6,176,575 million of loans and receivables, ￦934,390 million of available-for-sale financial assets, and ￦328,314 million of financial assets at fair value through profit or loss.

A financial asset is measured at amortized cost under IFRS 9 if the asset is held by the Group to collect its contractual cash flows and the asset’s contractual cash flows represent solely payments of principal and interest. As of December 31, 2017, the Group has ￦6,176,575 million of loans and receivables measured at amortized cost.

Based on preliminary assessment, most of the Group’s loans and receivables are held to collect their contractual cash flows and the asset’s contractual cash flows represent solely payments of principal and interest. Though some are held for collecting the asset’s contractual cash flows and sale, management does not expect this to have a significant impact due to the short term nature of the receivables.

A financial asset is measured at FVOCI under IFRS 9 if the objective of the business model is achieved both by collecting contractual cash flows and selling financial assets; and the asset’s contractual cash flows represent solely payments of principal and interest. As of December 31, 2017, the Group has ￦19,928 million of debt instruments classified as available-for-sale financial assets.

Most of the debt instruments held by the Group classified as available-for-sale financial assets are expected to be classified as financial assets measured at FVOCI upon adoption IFRS 9 as at January 1, 2018. Therefore, management does not expect there to be a significant impact.

Under IFRS 9, equity instruments that are not held for trading may be irrevocably designated as FVOCI on initial recognition with no recycling of amounts from OCI to profit and loss. As of December 31, 2017, the Group has ￦914,462 million of available-for-sale equity instruments.

As the Group plans to classify the equity instruments with long-term investment purposes to financial assets measured at FVOCI under IFRS 9, the Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements except no recycling of amounts from OCI to profit and loss is allowed.

All other financial assets are measured at FVTPL. As of December 31, 2017, the Group has ￦97,003 million of debt instruments classified as financial assets at FVTPL.

Most of the financial assets classified as FVTPL under IAS 39 of the Group are expected to be designated as financial assets measured at FVTPL under IFRS 9. Therefore, the Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements upon adoption of IFRS 9 as at January 1, 2018.

ii)    Classification and measurement of financial liabilities

Under IFRS 9, for the financial liabilities designated as FVTPL using the fair value option, the element of gains or losses attributable to changes in the own credit risk should normally be recognized in OCI, with the remainder recognized in profit or loss. These amounts recognized in OCI are not recycled to profit or loss even when the liability is derecognized. However, if presentation of the fair value change in respect of the liability’s credit risk in OCI results in or enlarges an accounting mismatch in profit or loss, gains and losses are entirely presented in profit or loss.

Adoption of IFRS 9 may result in decrease in profit or loss, since the amount of fair value changes that is attributable to changes in the credit risk of the liability will be presented in OCI.

As of December 31, 2017, the Group’s total financial liability amounts to ￦12,725,704 million, among which the financial liabilities designated as FVTPL using fair value option amount to ￦60,278 million.

As of December 31, 2017, most of the financial liabilities designated as FVTPL of the Group have short-term maturities with no significant changes in their credit risks. The Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements upon adoption of IFRS 9 as of January 1, 2018.

iii)    Impairment: financial assets and contract assets

The current impairment requirements under IAS 39 are based on an ‘incurred loss model’, where the impairment exists if there is objective evidence as a result of one or more events that occurred after the initial recognition of an asset. However, IFRS 9 replaces the incurred loss model in IAS 39 with an ‘expected credit loss model’ which applies to debt instruments measured at amortized cost or at fair value through other comprehensive income.

Under IFRS 9, the Group should recognize a loss allowance or provision at an amount equal to 12-month expected credit losses or lifetime expected credit losses for financial assets determined by the extent of probable credit deterioration since initial recognition as explained below. Therefore, the new impairment requirements are expected to result in earlier recognition of credit losses compared to the incurred loss model of IAS 39.

Stages(*1)		Loss allowances
Stage 1	No significant increase in credit risk since initial recognition(*2)	Loss allowances are determined for the amount of the expected credit losses that result from default events that are possible within 12 months after the reporting date.
Stage 2	Significant increase in credit risk since initial recognition	Loss allowances are determined for the amount of the expected credit losses that result from all possible default events over the expected life of the financial instrument.
Stage 3	Objective evidence of credit risk impairment

(*1) Under IFRS 15, Revenue from Contracts with Customers (see note 4 (28) (2)), for trade receivables and contract assets arising with no significant credit risk, loss allowances are recognized at an amount equal to lifetime expected credit losses. However, for trade receivables and contract assets with a significant financing component arising under IFRS 15, the Group may choose as its accounting policy to recognize loss allowances at an amount equal to lifetime expected credit losses. In addition, for receivables under lease arrangement, the Group may choose to recognize loss allowances at an amount equal to lifetime expected credit losses. The Group expects to perform the analysis on whether there was a significant increase in credit risk on collective basis instead of on individual instrument basis. In addition, when information that is more forward-looking than past due status is not available without undue cost or effort, the Group expects to use past due information to determine whether there have been significant increases in credit risk since initial recognition.

(*2) The Group may determine that a financial asset’s credit risk has not increased significantly if the asset has low credit risk at the reporting date.

IFRS 9 allows the Group to only recognize the cumulative changes in lifetime expected credit losses since initial recognition as a loss allowance for purchased or originated credit-impaired financial assets at the reporting date. As of December 31, 2017, the Group has ￦6,176,575 million of debt instrument financial assets measured at amortized cost and ￦362,171 million as loss allowances for these assets. The Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements upon adoption of IFRS 9 on January 1, 2018.

iv)    Hedge accounting

IFRS 9 maintains the mechanics of hedge accounting from those in IAS 39. However, IFRS 9 replaces existing rule-based requirements under IAS 39 that are complex and difficult to apply with principle based requirement focusing more on the Group’s risk management purposes and procedures. Under IAS 9, more hedging instruments and hedged items are permitted and 80%-125% effectiveness requirement is removed.

By complying with the hedging rules in IFRS 9, the Group may apply hedge accounting for transactions that currently do not meet the hedging criteria under IAS 39 thereby reducing volatility in profit or loss. As of December 31, 2017, the Group recognized the total amount of ￦2,026,434 million as hedged liabilities that applied hedge accounting and changes in fair value of cash flow hedge in the amount of ￦73,828 million was recognized in OCI for the year ended December 31, 2017.

Upon initial application of IFRS 9, the Group may choose as its accounting policy to continue to apply hedge accounting requirements under IAS 39 instead of the requirements in IFRS 9.

The Group is yet to decide on its accounting policy whether to continuously apply the hedge accounting requirements of IAS 39 instead of the requirements in IFRS 9 when initially applying IFRS 9. The Group designates derivatives such as currency swaps as hedging instruments to hedge the risk of variability in cash flows associated with the foreign currency debentures and borrowings. As the Group’s hedging instruments as of December 31, 2017 satisfy the hedge requirements of retrospective testing (80~125%) under IAS 39, the adoption of IFRS 9 is not expected to have material impact on the Group’s consolidated financial statements.

2)    IFRS 15, Revenue from Contracts with Customers

IFRS 15, Revenue from Contracts with Customers, published in May 2014 is effective for annual periods beginning on or after January 1, 2018, with early adoption permitted. It replaces existing revenue recognition guidance, including IAS 18, Revenue, IAS 11, Construction Contracts, SIC 31, Revenue: Barter Transactions Involving Advertising Services, International Financial Reporting Interpretations Committee (“IFRIC”) 13, Customer Loyalty Programs, IFRIC 15, Agreements for the Construction of Real Estate, and IFRIC 18, Transfers of Assets from Customers. The Group plans to adopt IFRS 15 on January 1, 2018. The Group plans to apply IFRS 15 by recognizing the cumulative effect of initially applying the IFRS 15 as an adjustment to the opening balance of retained earnings (or other component of equity, as appropriate) of the year beginning January 1, 2018. The Group elected to apply IFRS 15 retrospectively only to contracts that are not completed contracts at the date of initial application (January 1, 2018) using the transition method permitted by IFRS 15.

IAS 18 provides separate revenue recognition criteria by transaction type which include sale of goods, rendering of services, and use of entity assets by others yielding interest, royalties and dividends. However, IFRS 15 introduces a five-step model for revenue recognition that focuses on the ‘transfer of control’ rather than the ‘transfer of risks and rewards’. The steps in five-step model are as follows:

• identification of the contract with a customer;

• identification of the performance obligations in the contract;

• determination of the transaction price;

• allocation of the transaction price to the performance obligations in the contract; and

• recognition of revenue when (or as) the entity satisfies a performance obligation.

The Group performed evaluation and identified necessary changes to its accounting system and related controls based on the understanding of the revenue stream of the Group with the assistance of external information technology and accounting specialists. The Group is assessing the financial impact of the adoption of IFRS 15 on its consolidated financial statements and plans to complete the assessment by March 31, 2018.

Based on the circumstances and information available as of December 31, 2017, the Group preliminarily assessed the financial impact on its consolidated financial statements resulting from the adoption of IFRS 15. The results of the preliminary assessment are as follows. The results are subject to change according to the additional information available to use in subsequent periods.

i) Identification of performance obligations in the contract

A substantial portion of the Group’s revenues are generated from provision of wireless telecommunications services. IFRS 15 requires the Group to evaluate goods or services promised to customers to determine if they are performance obligations other than wireless telecommunications service that should be accounted for separately. The amount and timing of revenue recognition under IFRS 15 may be different from those under IAS 18 depending on the conclusion over the existence of separately identifiable performance obligations and the timing of satisfying each performance obligation.

In the case that the Group provides the wireless telecommunications services and a handset to one customer, the Group will allocate considerations from the customer between handset sale revenue and wireless telecommunications service revenue. The handset sales revenue is recognized when handset is sold and the wireless telecommunications service revenue is recognized as revenue over the period of the contract term as stated in the subscription contract.

ii) Allocate the transaction price to the separate performance obligations

In accordance with IFRS 15, the Group should allocate the transaction price to each performance obligation in a contract in proportion to their stand-alone selling price. The Group plans to use adjusted market assessment method for estimating the stand-alone selling price. However, in some circumstances, ‘expected cost plus a margin’ approach will be used.

The Group is in the progress of assessing the financial impact of allocating the transaction price to each performance obligation in a contract in proportion to their stand-alone selling price for the case where the Group provides the wireless telecommunications services and handset to one customer. Based on the preliminary assessment, the Group expects that wireless telecommunications service revenue will be decreased, while handset sale revenue will be increased upon adoption of IFRS 15.

iii) Incremental costs to acquire a contract

The Group has exclusive contracts with its sales agents to sell the Group’s wireless telecommunications services to subscribers. These agents receive commissions depending on the number of subscribers newly added and retained. The commissions paid to the agents constitute a significant portion of the Group’s operating expenses. Currently, the portion of these commissions that would not have been incurred if there have been no binding contracts with the subscribers are expensed.

Under IFRS 15, for the Group’s incremental costs to acquire a subscription contract, the Group expects to capitalize such amounts and amortized over the expected subscription period estimated based on historical experience. However, as a practical expedient, the Group plans to expense the incremental cost as incurred if the amortization period of the contract acquisition and fulfillment cost is considered to be not longer than one year.

As of December 31, 2017, the Group is assessing the impact of capitalizing the incremental costs associated with obtaining customer contracts. Based on the preliminary assessment, the Group expects commission expenses to decrease, while corresponding assets capitalized (incremental costs of obtaining a contract) and amortization expenses to be recognized and incurred, respectively.

3)    IFRS 16, Leases

IFRS 16, published in January 2016 is effective for annual periods beginning on or after January 1, 2019, with early adoption permitted. IFRS16 replaces existing leases guidance including IAS 17, Leases, IFRIC 4, Determining whether an Arrangement contains a Lease, SIC 15, Operating Leases — Incentives and SIC 27, Evaluating the Substance of Transactions Involving the Legal Form of a Lease.

IFRS 16, at the inception date of a contract and the first implementation of the standard, requires the Group to determine whether a contract is, or contains, a lease unless the Group applies the practical expedient for the existing lease contract at the date of adoption of the standard.

When accounting for lease, lessee and lessor should account for each lease component within the contract as a lease separately from non-lease components of the contract.

Lessee recognizes a right-of-use asset representing its right to use the underlying asset and a lease liability representing its obligation to make lease payments. However, there are optional exemptions for short-term leases and leases of low value items. As a practical expedient, a lessee may elect, by class of underlying asset, not to separate non-lease components from lease components, and instead account for each lease component and any associated non-lease components as a single lease component.

Lessor accounting remains similar to the current standard IAS 17. For a sale and leaseback arrangement, IFRS 16 requires the Group to apply the requirements for determining when a performance obligation is satisfied in IFRS 15 to determine whether the transfer of an asset is accounted for as a sale of that asset. However, sale and leaseback arrangements entered into before the adoption of IFRS 16 may not be reassessed.

i) Lease accounting for lessees

As a lessee, the Group can either apply the IFRS 16 using a full retrospective approach; or modified retrospective approach. The full retrospective approach requires the Group to retrospectively apply the new standard to each prior reporting period presented, while modified retrospective approach requires the lessee to recognize the cumulative effect of initial application at the date of initial application of the new leases standard.

ii) Lease accounting for lessors

In case where the Group is an intermediate lessor, the Group should reassess subleases that were classified as operating leases applying IAS 17 and are ongoing at the date of initial application, whether each sublease should be classified as an operating lease or a finance lease applying IFRS 16. For subleases that were classified as operating leases applying IAS 17 but finance leases applying IFRS 16, the Group should accounts for such sublease as a new finance lease entered into at the date of initial application of IFRS 16.

The Group plans to update its accounting system and related controls and complete the assessment of impact on its consolidated financial statements resulting from the adoption of IFRS 16 by December 31, 2018.

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Operating Segments

12 Months Ended

Dec. 31, 2017

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Operating Segments

5. Operating Segments

The Group’s operating segments have been identified to be each business unit, by which the Group provides independent services and merchandise. The Group’s reportable segments are cellular services, which include wireless voice and data transmission services, sales of wireless devices, IoT solutions and platform services; fixed-line telecommunication services, which include fixed-line telephone services, broadband Internet services, advanced media platform services (including IPTV) and business communications services; e-commerce services, which include open marketplace platform, 11st, and other commerce solutions, and other businesses, which include online portal service, hardware business and other operations that do not meet the quantitative thresholds to be separately considered reportable segments.

(1) Segment information for the years ended December 31, 2017, 2016 and 2015 is as follows:

(In millions of won)
	2017
	Cellular Services		Fixed-line telecommu- nication services		E-commerce Services			Others			Sub-total		Adjustments			Total
Total revenue	￦	14,873,543		3,586,887		1,091,903			788,836			20,341,169		(2,821,156	)		17,520,013
Inter-segment revenue		1,611,408		862,736		47,732			299,280			2,821,156		(2,821,156	)		—
External revenue		13,262,135		2,724,151		1,044,171			489,556			17,520,013		—			17,520,013
Depreciation and amortization		2,390,016		592,877		54,486			60,087			3,097,466		—			3,097,466
Operating profit (loss)		1,714,078		167,515		(267,829	)		(77,138	)		1,536,626		(312,054	)		1,224,572
Gain relating to investments in subsidiaries, associates and joint ventures, net																	2,245,732
Finance income																	366,561
Finance costs																	(433,616	)
Profit before income tax																	3,403,249

(In millions of won)
	2016
	Cellular Services		Fixed-line telecommu- nication services		E-commerce Services			Others			Sub-total		Adjustments			Total
Total revenue	￦	14,635,720		3,349,905		1,177,323			726,374			19,889,322		(2,797,506	)		17,091,816
Inter-segment revenue		1,630,811		698,712		176,007			291,976			2,797,506		(2,797,506	)		—
External revenue		13,004,909		2,651,193		1,001,316			434,398			17,091,816		—			17,091,816
Depreciation and amortization		2,262,363		551,811		68,298			59,414			2,941,886		—			2,941,886
Operating profit (loss)		1,799,127		132,459		(365,194	)		(30,648	)		1,535,744		(232,326	)		1,303,418
Gain relating to investments in subsidiaries, associates and joint ventures, net																	544,501
Finance income																	575,050
Finance costs																	(326,830	)
Profit before income tax																	2,096,139
(In millions of won)
	2015
	Cellular Services		Fixed-line telecommu- nication services		E-commerce Services			Others			Sub-total		Adjustments			Total
Total revenue	￦	14,962,689		3,162,712		1,703,278			410,265			20,238,944		(3,102,210	)		17,136,734
Inter-segment revenue		1,693,411		668,139		643,299			97,361			3,102,210		(3,102,210	)		—
External revenue		13,269,278		2,494,573		1,059,979			312,904			17,136,734		—			17,136,734
Depreciation and amortization		2,174,819		531,106		112,537			26,833			2,845,295		—			2,845,295
Operating profit (loss)		1,678,339		108,252		(6,740	)		(71,845	)		1,708,006		(212,581	)		1,495,425
Gain relating to investments in subsidiaries, associates and joint ventures, net																	786,140
Finance income																	103,900
Finance costs																	(350,100	)
Profit before income tax																	2,035,365

(2) Reconciliation of total segment operating income to consolidated operating profit from continuing operations for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)	2017			2016			2015
Total segment operating income	￦	1,536,626			1,535,744			1,708,006
Other operating income:
Gain on disposal of property and equipment and intangible assets		13,991			6,908			7,140
Others(*1)		18,006			59,640			23,795
		31,997			66,548			30,935
Other operating expenses:
Impairment loss on property and equipment and intangible assets		(54,946	)		(24,506	)		(35,845	)
Loss on disposal of property and equipment and intangible assets		(60,086	)		(63,797	)		(21,392	)
Donations		(112,634	)		(96,633	)		(72,454	)
Bad debt for accounts receivable — other		(5,793	)		(40,312	)		(15,323	)
Others(*2)		(110,592	)		(73,626	)		(98,502	)
		(344,051	)		(298,874	)		(243,516	)
Consolidated operating profit from continuing operations	￦	1,224,572			1,303,418			1,495,425

(*1) Others for the year ended December 31, 2016 include ￦25 billion of penalty refund.

(*2) Others for the years ended December 31, 2017, 2016 and 2015 primarily consist of ￦21.4 billion, ￦7.6 billion and ￦29.5 billion of penalties, respectively, and various other expenses with inconsequential amounts.

Since there are no intersegment sales of inventory or depreciable assets, there is no unrealized intersegment profit to be eliminated on consolidation. Domestic revenue for the years ended December 31, 2017, 2016 and 2015 amounts to ￦17,374 billion, ￦16,940 billion and ￦17,083 billion, respectively. Domestic non-current assets (excluding financial assets, investments in associates and joint ventures and deferred tax assets) as of December 31, 2017, 2016 and 2015 amount to ￦15,554 billion, ￦15,949 billion and ￦14,474 billion, and non-current assets outside of Korea amount to ￦257 billion, ￦286 billion and ￦287 billion, respectively.

No single customer contributed 10% or more to the Group’s total sales for the years ended December 31, 2017, 2016 and 2015.

(3) The Group’s operating revenue by service type is as follows:

(In millions of won)
	2017		2016		2015
Cellular revenue:
Wireless service(*1)	￦	10,638,961		10,582,963		10,720,518
Cellular interconnection		592,754		614,446		710,026
Wireless device sales		1,052,203		922,449		963,354
Miscellaneous(*2)		978,217		885,051		875,380
		13,262,135		13,004,909		13,269,278
Fixed-line telecommunication services revenue:
Fixed line telephone service		316,763		357,754		420,611
Fixed line interconnection		116,070		134,089		57,130
Broadband internet service and advanced media platform service		1,641,645		1,472,776		1,308,789
International calling service		89,412		95,986		99,106
Miscellaneous(*3)		560,261		590,588		608,937
		2,724,151		2,651,193		2,494,573
E-commerce services revenue(*4)		1,044,171		1,001,316		1,059,979
Other revenue:
Portal service(*5)		43,952		54,177		71,812
Miscellaneous(*6)		445,604		380,221		241,092
		489,556		434,398		312,904
Consolidated operating revenue	￦	17,520,013		17,091,816		17,136,734

(*1) Wireless service revenue includes revenue from wireless voice and data transmission services principally derived through monthly plan-based fees, usage charges for outgoing voice calls, usage charges for wireless data services and value-added service fees paid by our wireless subscribers.

(*2) Miscellaneous cellular services revenue includes revenue from IoT solutions as well as other miscellaneous cellular services.

(*3) Miscellaneous fixed-line telecommunication services revenue includes revenues from business communications services (other than fixed-line telephone service) provided by SK Broadband and VoIP services provided by SK Telink

(*4) E-commerce service revenue includes revenues from 11st, open marketplace platform, and other commerce solutions.

(*5) Portal service revenue includes revenues from Nate, and online portal service operated by SK Communications.

(*6) Miscellaneous other revenue includes revenues from hardware business, security business operated by one of the Group’s subsidiaries, NSOK Co., Ltd., marketing and sales solutions business operated by one of the Group’s subsidiaries, SK m&service Co., Ltd., and online open marketplace for mobile applications among other operations.

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Restricted Deposits

12 Months Ended

Dec. 31, 2017

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Restricted Deposits

6. Restricted Deposits

Deposits which are restricted in use as of December 31, 2017 and 2016 are summarized as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Short-term financial instruments(*)	￦	89,850		90,278
Long-term financial instruments(*)		1,222		937
	￦	91,072		91,215

(*) Financial instruments include charitable trust fund established by the Group where profits from the fund are donated to charitable institutions. As of December 31, 2017, the funds cannot be withdrawn before maturity.

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Trade and Other Receivables

12 Months Ended

Dec. 31, 2017

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Trade and Other Receivables

7. Trade and Other Receivables

(1) Details of trade and other receivables as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Gross amount		Allowances for doubtful accounts			Carrying amount
Current assets:
Accounts receivable — trade	￦	2,365,270		(239,263	)		2,126,007
Short-term loans		63,380		(550	)		62,830
Accounts receivable — other		1,336,247		(75,412	)		1,260,835
Accrued income		3,979		—			3,979
Others		3,927		—			3,927
		3,772,803		(315,225	)		3,457,578
Non-current assets:
Long-term loans		97,635		(46,761	)		50,874
Long-term accounts receivable — other		287,048		—			287,048
Guarantee deposits		292,590		—			292,590
Long-term accounts receivable — trade		12,933		(185	)		12,748
		690,206		(46,946	)		643,260
	￦	4,463,009		(362,171	)		4,100,838

(In millions of won)
	December 31, 2016
	Gross amount		Allowances for doubtful accounts			Carrying amount
Current assets:
Accounts receivable — trade	￦	2,482,502		(241,576	)		2,240,926
Short-term loans		59,526		(547	)		58,979
Accounts receivable — other		1,200,421		(78,977	)		1,121,444
Accrued income		2,780		—			2,780
Others		3,937		—			3,937
		3,749,166		(321,100	)		3,428,066
Non-current assets:
Long-term loans		113,456		(47,980	)		65,476
Long-term accounts receivable — other		149,669		—			149,669
Guarantee deposits		298,964		—			298,964
Long-term accounts receivable — trade		20,637		(252	)		20,385
		582,726		(48,232	)		534,494
	￦	4,331,892		(369,332	)		3,962,560

(2) Changes in allowances for doubtful accounts of trade and other receivables for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Balance at January 1	￦	369,332			344,016
Bad debt expense		40,377			78,132
Write-offs		(70,802	)		(79,891	)
Other		23,264			27,075
Balance at December 31	￦	362,171			369,332

(3) Details of overdue but not impaired, and impaired trade and other receivables as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017						December 31, 2016
	Accounts receivable - trade			Other receivables			Accounts receivable - trade			Other receivables
Neither overdue nor impaired	￦	1,585,714			1,930,261			1,715,966			1,617,349
Overdue but not impaired		29,304			3,113			41,613			5,663
Impaired		763,185			151,432			745,560			205,741
		2,378,203			2,084,806			2,503,139			1,828,753
Allowances for doubtful accounts		(239,448	)		(122,723	)		(241,828	)		(127,504	)
	￦	2,138,755			1,962,083			2,261,311			1,701,249

The Group establishes allowances for doubtful accounts based on the likelihood of recoverability of trade and other receivables based on their aging at the end of the period, past customer default experience, customer credit status, and economic and industrial factors.

(4) The aging of overdue but not impaired accounts receivable as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017				December 31, 2016
	Accounts receivable - trade		Other receivables		Accounts receivable - trade		Other receivables
Less than 1 month	￦	7,150		2,679		11,543		2,838
1 ~ 3 months		1,663		44		9,144		140
3 ~ 6 months		1,576		124		4,643		1
More than 6 months		18,915		266		16,283		2,684
	￦	29,304		3,113		41,613		5,663

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Inventories

12 Months Ended

Dec. 31, 2017

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Inventories

8. Inventories

Details of inventories as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017							December 31, 2016
	Acquisition cost		Write-down			Carrying amount		Acquisition cost		Write-down			Carrying amount
Merchandise	￦	251,463		(7,488	)		243,975		232,871		(6,913	)		225,958
Finished goods		1,889		(557	)		1,332		1,931		(363	)		1,568
Work-in-process		1,906		(956	)		950		2,895		(347	)		2,548
Raw materials and supplies		29,395		(3,249	)		26,146		31,141		(1,369	)		29,772
	￦	284,653		(12,250	)		272,403		268,838		(8,992	)		259,846

The amount of the inventory write-downs and write-off of inventories charged to statement of income are as follows:

(In millions of won)
	2017			2016			2015
Charged to cost of products that have been resold	￦	6,079			3,751			1,983
Write-off upon sale		(2,820	)		(1,299	)		(2,095	)

There are no significant reversals of inventory write-downs for the periods presented.

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Investment Securities

12 Months Ended

Dec. 31, 2017

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Investment Securities

9. Investment Securities

(1) Details of short-term investment securities as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Beneficiary certificates(*)	￦	144,386		107,364

(*) The income distributable in relation to beneficiary certificates as of December 31, 2017 were accounted for as accrued income.

(2) Details of long-term investment securities as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Equity securities:
Marketable equity securities(*1)	￦	589,202		526,363
Unlisted equity securities etc.(*2)		277,877		295,403
		867,079		821,766
Debt securities:
Investment bonds		19,928		6,755
	￦	887,007		828,521

(*1) During the year ended December 31, 2016, the Group sold 3,793,756 shares of Loen Entertainment, Inc. to Kakao Corp. in exchange for 1,357,367 shares of Kakao Corp. and ￦218,037 million in cash. In connection with the sale of Loen Entertainment shares, the Group recognized gain on disposal of long-term investment securities amounting to ￦314,745 million.

The Group recognized gain on disposal amounting to ￦138,779 million as the Group disposed its entire marketable equity securities of POSCO Co., Ltd. for ￦305,110 million of cash during the year ended December 31, 2016.

In addition, the Group sold 1,357,367 shares of Kakao Corp. in exchange for ￦112,649 million in cash during the year ended December 31, 2017. In connection with the sale of Kakao Corp. shares, the Group recognized loss on disposal of long-term investment securities amounting to ￦35,468 million.

(*2) Unlisted equity securities and equity investments whose fair value cannot be measured reliably are recorded at cost.

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Business Combination

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Business Combination

10. Business Combination

(1) 2017

1) Acquisition of S.M. LIFE DESIGN COMPANY JAPAN INC. by IRIVER LIMITED

On September 1, 2017, IRIVER LIMITED, a subsidiary of the Parent Company, acquired all of the S.M. LIFE DESIGN COMPANY JAPAN INC.’s shares from S.M. ENTERTAINMENT JAPAN, Inc. in order to enter overseas business and enhance its competitiveness with the consideration of ￦30,000 million in cash. The Group recognized the difference between the consideration paid and the fair value of net assets acquired amounting to ￦21,748 million as goodwill. Subsequent to the acquisition, S.M. LIFE DESIGN COMPANY JAPAN INC. recognized revenues and net profit of amounting to ￦6,365 million and ￦1,244 million, respectively, in 2017.

2) Merger of SM mobile communications Co., Ltd. by IRIVER LIMITED

On October 1, 2017, IRIVER LIMITED merged SM mobile communications Co., Ltd. in order to enter contents business and enhance competitiveness of its device business. As a result of merger, IRIVER LIMITED obtained control over S.M. Mobile Communications JAPAN Inc. which was wholly owned by SM mobile communications Co., Ltd. The consideration transferred was measured at the fair value of the shares transferred based on the merger ratio set on October 1, 2017. The Group recognized the difference between the consideration and the fair value of net assets amounting to ￦13,473 million as goodwill. Subsequent to the consummation of the merger, S.M. Mobile Communications JAPAN Inc. recognized no revenue with ￦103 million of net loss in 2017.

3) Considerations paid and assets and liabilities recognized at the acquisition date are as follows:

(In millions of won)
	S.M. LIFE DESIGN COMPANY JAPAN INC.			S.M. Mobile Communications JAPAN Inc.
Considerations paid:
Cash and cash equivalents	￦	30,000			—
Shares of IRIVER LIMITED		—			24,650
Assets and liabilities acquired:
Cash and cash equivalents	￦	3,434			4,112
Trade and other receivables		1,471			237
Inventories		1,879			—
Property and equipment		4			311
Intangible assets		6,677			7,445
Other assets		—			41
Trade and other payables		(2,563	)		(815	)
Deferred tax liabilities		(2,324	)		—
Other liabilities		(326	)		(154	)
Net assets	￦	8,252			11,177

(2) 2015

1) General information

On April 1, 2015, Neosnetworks Co., Ltd., a subsidiary of the Parent Company, acquired an unmanned machine security business of Joeun Safe Co., Ltd., which provides security and maintenance services, in order to expand infrastructure and enhance competitiveness of its security business.

The Group recognized the acquired assets and liabilities at fair value and the difference between the consideration and fair value of net assets as goodwill.

2) Considerations paid and identifiable assets acquired and liabilities assumed

Considerations paid and assets in succession recognized at the acquisition date are as follows:

(In millions of won)
	2015
Considerations paid and liabilities assumed:
Cash and cash equivalents	￦	13,197
Accounts payable — other		1,858
	￦	15,055
Assets acquired:
Property and equipment	￦	3,208
Intangible assets		8,486
Other assets		1,603
	￦	13,297

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Business Combinations under Common Control

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Business Combinations under Common Control

11. Business Combinations under Common Control

(1) 2016

During the year ended December 31, 2016, the Parent Company distributed its entire ownership interests in Neosnetworks Co., Ltd. to SK Telink Co., Ltd., a subsidiary of the Parent Company as contribution in kind. Neosnetworks Co., Ltd. became a wholly owned subsidiary of SK Telink Co., Ltd. As this transaction is a business combination under common control, SK Telink Co., Ltd. recognized the book value of the assets and liabilities of Neosnetworks Co., Ltd. in its financial statements. There’s no effect on the assets and liabilities of the consolidated financial statements.

(2) 2015

During the year ended December 31, 2015, hoppin service division of SK Planet Co., Ltd., a subsidiary of the Parent Company, was spun off from SK Planet Co., Ltd. and was merged into SK Broadband, Co., Ltd., a subsidiary of the Parent Company. There is no impact on the consolidated financial statements as it is a business combination under common control.

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Investments in Associates and Joint Ventures

12 Months Ended

Dec. 31, 2017

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Investments in Associates and Joint Ventures

12. Investments in Associates and Joint Ventures

(1) Investments in associates and joint ventures accounted for using the equity method as of December 31, 2017 and 2016 are as follows:

(In millions of won)
		December 31, 2017				December 31, 2016
	Country	Ownership (%)		Carrying amount		Ownership (%)		Carrying amount
Investments in associates:
SK China Company Ltd.(*1)	China		27.3	￦	526,099		9.6	￦	46,354
Korea IT Fund(*2)	Korea		63.3		257,003		63.3		263,850
KEB HanaCard Co., Ltd.(*3)	Korea		15.0		280,988		15.0		265,798
NanoEnTek, Inc.	Korea		28.5		38,718		28.5		39,514
SK Industrial Development China Co., Ltd.(*1)	Hong Kong		—		—		21.0		74,717
SK Technology Innovation Company	Cayman Islands		49.0		42,511		49.0		47,488
HappyNarae Co., Ltd.(*4)	Korea		45.0		21,873		42.5		17,236
SK hynix Inc.	Korea		20.1		8,130,000		20.1		6,132,122
SK MENA Investment B.V.	Netherlands		32.1		13,853		32.1		15,451
SKY Property Mgmt. Ltd.(*1)	Virgin Island		—		—		33.0		263,225
S.M. Culture & Contents Co., Ltd.(*5)	Korea		23.4		64,966		—		—
Xian Tianlong Science and Technology Co., Ltd.	China		49.0		25,891		49.0		25,880
Daehan Kanggun BcN Co., Ltd. and others	—		—		96,479		—		115,181
Sub-total					9,498,381				7,306,816
Investments in joint ventures:
Dogus Planet, Inc.(*6)	Turkey		50.0		13,991		50.0		20,081
PT XL Planet Digital(*7)	Indonesia		—		—		50.0		27,512
Finnq Co., Ltd.(*8)	Korea		49.0		16,474		49.0		24,174
Celcom Planet and others	—		—		9,592		—		25,740
Sub-total					40,057				97,507
Total				￦	9,538,438			￦	7,404,323

(*1) During the year ended December 31, 2017, the Group contributed its shares in SKY Property Mgmt. Ltd. and SK Industrial Development China Co., Ltd., both equity method investees of the Group, to SK China Company Ltd., and participated in SK China Company Ltd.’s rights issue amounting to USD 100,000,000, which resulted in Group’s acquiring 8,101,884 and 2,107,037 shares of SK China Company Ltd., respectively. This investment in associates acquired through this contribution in kind transaction was measured at fair value.

(*2) Investment in Korea IT Fund was classified as investment in associates as the Group does not have control over Korea IT Fund under the contractual agreement with other shareholders.

(*3) This investment was classified as investments in associates as the Group can exercise significant influence through its right to appoint the members of board of directors even though the Group has less than 20% of equity interests.

(*4) The Group acquired 40,000 shares of HappyNarae Co., Ltd. at ￦17,212 per share during the year ended December 31, 2017.

(*5) During the year ended December 31, 2017, the Group subscribed to a third-party allocation of new shares of 22,033,898 by S.M. Culture & Contents Co., Ltd. at ￦65,341 million in cash.

(*6) The investment is held by SK Planet Co., Ltd.

(*7) PT XL Planet Digital was disposed during the year ended December 31, 2017.

(*8) Investment in Finnq Co., Ltd. was classified as investment in joint venture as the Group has joint control pursuant to the agreement with the other shareholders.

(2) The market price of investments in listed associates as of December 31, 2017 and 2016 are as follows:

(In millions of won, except for share data)
	December 31, 2017						December 31, 2016
	Market value per share (in won)		Number of shares		Fair value		Market value per share (in won)		Number of shares		Fair value
NanoEnTek, Inc.	￦	5,950		6,960,445		41,415		5,020		6,960,445		34,941
SK hynix Inc.		76,500		146,100,000		11,176,650		44,700		146,100,000		6,530,670
S.M. Culture & Contents Co., Ltd.		2,700		22,033,898		59,492		—		—		—

(3) The financial information of significant associates as of December 31, 2017 and 2016 and for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	As of December 31, 2017
	SK hynix Inc.(*)			KEB HanaCard Co., Ltd. (*)			SK China Company Ltd. (*)
Current assets	￦	17,310,444			7,339,492			729,872
Non-current assets		28,108,020			220,258			1,031,647
Current liabilities		8,116,133			1,181,746			81,161
Non-current liabilities		3,481,412			4,861,842			64,717
	2017
Revenue		30,109,434			1,519,607			69,420
Profit for the year		10,642,219			106,352			11,492
Other comprehensive income (loss)		(422,042	)		(984	)		27,190
Total comprehensive income		10,220,177			105,368			38,682

(*) The financial information of SK hynix Inc., KEB HanaCard Co., Ltd., and SK China Company Ltd. are consolidated financial information.

(In millions of won)
	As of December 31, 2016
	SK hynix Inc.(*)		KEB HanaCard Co., Ltd.(*)
Current assets	￦	9,838,982		6,868,387
Non-current assets		22,377,044		239,758
Current liabilities		4,160,849		1,219,327
Non-current liabilities		4,031,647		4,476,979
	2016
Revenue		17,197,975		1,413,077
Profit for the year		2,960,483		75,595
Other comprehensive income (loss)		28,844		(154	)
Total comprehensive income		2,989,327		75,441

(*) The financial information of SK hynix Inc. and KEB HanaCard Co., Ltd. are consolidated financial information.

(In millions of won)
	SK hynix Inc.		KEB HanaCard Co., Ltd.
	2015
Revenue	￦	18,797,998		1,472,830
Profit for the year		4,323,595		10,119
Other comprehensive income (loss)		40,215		(547	)
Total comprehensive income		4,363,810		9,572

(4) The condensed financial information of joint ventures as of December 31, 2017 and 2016 and for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	Dogus Planet, Inc.			Finnq Co., Ltd.
	As of December 31, 2017
Current assets	￦	39,656			32,232
Cash and cash equivalents		25,818			4,590
Non-current assets		21,159			15,610
Current liabilities		32,622			5,685
Accounts payable, other payables and provision		2,743			2,290
Non-current liabilities		212			13,862
	2017
Revenue		82,791			—
Depreciation and amortization		(6,152	)		(1,077	)
Interest income		781			532
Interest expense		(4	)		(276	)
Loss for the year		(4,535	)		(15,699	)
Total comprehensive loss		(4,535	)		(15,699	)

(In millions of won)
	Dogus Planet, Inc.			PT XL Planet Digital			Finnq Co., Ltd.
	As of December 31, 2016
Current assets	￦	46,433			20,077			48,699
Cash and cash equivalents		45,839			14,985			48,408
Non-current assets		20,218			50,765			673
Current liabilities		26,417			14,513			138
Accounts payable, other payables and provision		1,971			10,306			15
Non-current liabilities		72			1,305			784
	2016
Revenue		53,864			9,492			—
Depreciation and amortization		(5,299	)		(940	)		(12	)
Interest income		394			267			182
Interest expense		(2,139	)		—			—
Income tax benefit		—			51			—
Loss for the year		(22,017	)		(49,438	)		(829	)
Total comprehensive loss		(22,017	)		(49,438	)		(829	)

(In millions of won)
	Dogus Planet, Inc.			PT. Melon Indonesia			PT XL Planet Digital
	2015
Revenue	￦	38,944			17,094			5,536
Depreciation and amortization		(5,318	)		(132	)		(2,746	)
Interest income		465			288			525
Income tax benefit		—			—			7,025
Profit (Loss) for the year		(32,713	)		1,853			(21,381	)
Total comprehensive income (loss)		(32,713	)		1,853			(21,381	)

(5) Reconciliations of financial information of significant associates to carrying amounts of investments in associates in the consolidated financial statements as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Net assets		Ownership interests (%)		Net assets attributable to the ownership interests		Cost-book value differentials		Carrying amount
Associates:
SK hynix Inc.(*1,2)	￦	33,814,467		20.1		6,997,560		1,132,440		8,130,000
KEB HanaCard Co., Ltd.		1,516,162		15.0		227,424		53,564		280,988
SK China Company Ltd.(*1)		1,612,899		27.3		439,857		86,242		526,099

(In millions of won)
	December 31, 2016
	Net assets		Ownership interests (%)		Net assets attributable to the ownership interests		Cost-book value differentials		Carrying amount
Associates:
SK hynix Inc.(*1,2)	￦	24,016,955		20.1		4,970,267		1,161,855		6,132,122
KEB HanaCard Co., Ltd.		1,411,839		15.0		211,776		54,022		265,798

(*1) Net assets of these entities represent net assets excluding those attributable to their non-controlling interests.

(*2) The ownership interest is based on the number of shares owned by the Parent Company as divided by the total shares issued by the investee company. The Group applied the equity method using the effective ownership interest of 20.69% which is based on the number of shares owned by the Parent Company and the total issued shares outstanding less investee’s treasury shares.

(6) Details of the changes in investments in associates and joint ventures accounted for using the equity method for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)	2017
	Beginning balance		Acquisition and disposition			Share of profit (loss)			Other compre- hensive income (loss)			Impair- ment loss			Other increase (decrease)			Ending balance
Investments in associates
SK China Company Ltd.(*1)	￦	46,354		113,803			2,707			(36,783	)		—			400,018			526,099
Korea IT Fund(*2)		263,850		—			(8,815	)		3,371			—			(1,403	)		257,003
KEB HanaCard Co., Ltd.		265,798		—			15,494			(304	)		—			—			280,988
NanoEnTek, Inc.		39,514		—			(733	)		(63	)		—			—			38,718
SK Industrial Development China Co., Ltd.(*1)		74,717		—			5,154			(1,092	)		—			(78,779	)		—
SK Technology Innovation Company		47,488		—			433			(5,410	)		—			—			42,511
HappyNarae Co., Ltd.		17,236		688			3,929			20			—			—			21,873
SK hynix Inc.(*2)		6,132,122		—			2,175,887			(90,349	)		—			(87,660	)		8,130,000
SK MENA Investment B.V.		15,451		—			131			(1,729	)		—			—			13,853
SKY Property Mgmt. Ltd.(*1)		263,225		—			2,362			1,141			—			(266,728	)		—
S.M. Culture & Contents Co., Ltd.		—		65,341			(375	)		—			—			—			64,966
Xian Tianlong Science and Technology Co., Ltd.		25,880		—			11			—			—			—			25,891
Daehan Kanggun BcN Co., Ltd. and others(*2)		115,181		(1,306	)		(6,924	)		(2,723	)		(1,311	)		(6,438	)		96,479
Sub-total		7,306,816		178,526			2,189,261			(133,921	)		(1,311	)		(40,990	)		9,498,381
Investments in joint ventures
Dogus Planet, Inc.		20,081		2,162			(2,267	)		(5,985	)		—			—			13,991
PT XL Planet Digital(*3)		27,512		(18,864	)		(8,648	)		—			—			—			—
Finnq Co., Ltd		24,174		—			(7,691	)		(9	)		—			—			16,474
Celcom Planet and others		25,740		—			(6,228	)		(833	)		—			(9,087	)		9,592
Sub-total		97,507		(16,702	)		(24,834	)		(6,827	)		—			(9,087	)		40,057
Total	￦	7,404,323		161,824			2,164,427			(140,748	)		(1,311	)		(50,077	)		9,538,438

(*1) Other increase (decrease) is due to merger of SK China Company Ltd., SK Industrial Development China Co., Ltd. and SKY Property Mgmt. Ltd.

(*2) Dividends received from the associates are deducted from the carrying amount during the year ended December 31, 2017.

(*3) During the year ended December 31, 2017, the Group disposed the shares of PT XL Planet Digital and recognized loss on disposal of ￦27,900 million.

(In millions of won)
	2016
	Beginning balance		Acquisition and disposition			Share of profit (loss)			Other compre- hensive income (loss)			Impair- ment loss			Other increase (decrease)			Ending balance
Investments in associates
SK China Company Ltd.	￦	43,814		—			2,257			283			—			—			46,354
Korea IT Fund(*1)		260,456		—			14,864			(5,388	)		—			(6,082	)		263,850
KEB HanaCard Co., Ltd.		254,177		—			11,658			(37	)		—			—			265,798
Candle Media Co., Ltd.		20,144		(18,860	)		(673	)		(611	)		—			—			—
NanoEnTek, Inc.		45,008		—			(3,950	)		(1,544	)		—			—			39,514
SK Industrial Development China Co., Ltd.		86,324		—			(6,298	)		(5,309	)		—			—			74,717
SK Technology Innovation Company		45,891		—			162			1,435			—			—			47,488
HappyNarae Co., Ltd.		17,095		—			240			(99	)		—			—			17,236
SK hynix Inc.(*1)		5,624,493		—			572,086			8,593			—			(73,050	)		6,132,122
SK MENA Investment B.V.		14,929		—			63			459			—			—			15,451
SKY Property Mgmt. Ltd.		251,166		—			16,066			(4,007	)		—			—			263,225
Xian Tianlong Science and Technology Co., Ltd.		25,767		—			113			—			—			—			25,880
Daehan Kanggun BcN Co., Ltd. and others		161,058		(26,798	)		(13,179	)		754			(6,972	)		318			115,181
Sub-total		6,850,322		(45,658	)		593,409			(5,471	)		(6,972	)		(78,814	)		7,306,816
Investments in joint ventures
Dogus Planet, Inc.		15,118		18,722			(11,008	)		(2,751	)		—			—			20,081
PT. Melon Indonesia(*2)		4,339		(3,488	)		918			(1,769	)		—			—			—
PT XL Planet Digital		23,108		29,123			(24,719	)		—			—			—			27,512
Finnq Co., Ltd		—		24,580			(406	)		—			—			—			24,174
Celcom Planet and others		3,406		43,769			(21,435	)		—			—			—			25,740
Sub-total		45,971		112,706			(56,650	)		(4,520	)		—			—			97,507
Total	￦	6,896,293		67,048			536,759			(9,991	)		(6,972	)		(78,814	)		7,404,323

(*1) Dividends received from the associate are deducted from the carrying amount during the year ended December 31, 2016.

(*2) During the year ended December 31, 2016, the Group disposed of all shares of PT. Melon Indonesia and recognized gain on disposal of ￦11,634 million.

(7) The Group discontinued the application of equity method to the following investees due to their carrying amounts being reduced to zero. The details of cumulative unrecognized equity method losses as of December 31, 2017 are as follows:

(In millions of won)
	Unrecognized loss (profit)					Unrecognized change in equity
	Year ended December 31, 2017			Cumulative loss		Year ended December 31, 2017		Cumulative loss
Wave City Development Co., Ltd.	￦	(1,190	)		2,100		—		—
Daehan Kanggun BcN Co., Ltd. and others		(5,475	)		5,316		—		365
	￦	(6,665	)		7,416		—		365

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Property and Equipment

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Property and Equipment

13. Property and Equipment

(1) Property and equipment as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Acquisition cost		Accumulated depreciation			Accumulated impairment loss			Carrying amount
Land	￦	862,861		—			—			862,861
Buildings		1,638,749		(756,099	)		—			882,650
Structures		866,909		(488,334	)		—			378,575
Machinery		30,343,739		(23,262,762	)		(1,179	)		7,079,798
Other		1,722,441		(1,188,893	)		(2,491	)		531,057
Construction in progress		409,941		—			—			409,941
	￦	35,844,640		(25,696,088	)		(3,670	)		10,144,882

(In millions of won)
	December 31, 2016
	Acquisition cost		Accumulated depreciation			Accumulated impairment loss			Carrying amount
Land	￦	835,909		—			—			835,909
Buildings		1,604,863		(704,891	)		—			899,972
Structures		812,010		(453,055	)		—			358,955
Machinery		29,705,088		(22,667,047	)		(1,991	)		7,036,050
Other		1,701,794		(1,138,303	)		(457	)		563,034
Construction in progress		680,292		—			—			680,292
	￦	35,339,956		(24,963,296	)		(2,448	)		10,374,212

(2) Changes in property and equipment for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017
	Beginning balance		Acquisition		Disposal			Transfer(*)			Depreci- ation			Impair- ment			Business Combination		Other			Ending balance
Land	￦	835,909		13,093		(4,449	)		18,308			—			—			—		—			862,861
Buildings		899,972		5,098		(477	)		29,614			(51,557	)		—			—		—			882,650
Structures		358,955		46,614		(74	)		8,386			(35,306	)		—			—		—			378,575
Machinery		7,036,050		656,731		(41,692	)		1,644,045			(2,214,524	)		(778	)		—		(34	)		7,079,798
Other		563,034		720,431		(9,252	)		(597,404	)		(143,261	)		(2,234	)		315		(572	)		531,057
Construction in progress		680,292		1,317,389		(4,172	)		(1,583,560	)		—			—			—		(8	)		409,941
	￦	10,374,212		2,759,356		(60,116	)		(480,611	)		(2,444,648	)		(3,012	)		315		(614	)		10,144,882

(*) Includes reclassification to intangible assets.

(In millions of won)
	2016
	Beginning balance		Acquisition		Disposal			Transfer(*)			Depreciation			Impairment			Ending balance
Land	￦	812,947		2,464		(3,514	)		24,012			—			—			835,909
Buildings		911,129		4,637		(9,176	)		43,910			(50,528	)		—			899,972
Structures		344,221		33,802		(33	)		15,145			(34,180	)		—			358,955
Machinery		7,342,009		660,629		(45,672	)		1,234,737			(2,152,725	)		(2,928	)		7,036,050
Other		473,438		807,047		(6,052	)		(568,644	)		(142,700	)		(55	)		563,034
Construction in progress		487,512		1,154,424		(9,710	)		(951,934	)		—			—			680,292
	￦	10,371,256		2,663,003		(74,157	)		(202,774	)		(2,380,133	)		(2,983	)		10,374,212

(*) Includes reclassification to intangible assets.

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Investment Property

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Investment Property

14. Investment Property

(1) There are no investment property as of December 31, 2017 and 2016.

(2) Changes in investment properties for the year ended December 31, 2016 are as follows:

(In millions of won)
	2016
	Beginning balance		Reclassification(*)			Depreciation			Ending balance
Land	￦	10,634		(10,634	)		—			—
Buildings		4,437		(4,334	)		(103	)		—
	￦	15,071		(14,968	)		(103	)		—

(*) Includes reclassification to property and equipment.

(3) Income and expenses from investment property for the years ended December 31, 2016 and 2015 are as follows:

(In millions of won)
	2016			2015
Rent revenue	￦	386			850
Operating expense		(114	)		(240	)

XML

Goodwill

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Goodwill

15. Goodwill

(1) Goodwill as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Goodwill related to acquisition of Shinsegi Telecom, Inc.	￦	1,306,236		1,306,236
Goodwill related to acquisition of SK Broadband Co., Ltd.		358,443		358,443
Other goodwill		250,338		267,773
	￦	1,915,017		1,932,452

Goodwill is allocated to the following CGUs for the purpose of impairment testing.

• goodwill related to Shinsegi Telecom, Inc.(*1): cellular services;

• goodwill related to SK Broadband Co., Ltd.(*2): fixed-line telecommunication services; and

• other goodwill: e-commerce and other.

(*1) Goodwill related to acquisition of Shinsegi Telecom, Inc.

The recoverable amount of the CGU is based on its value in use calculated by applying the annual discount rate of 6.6% to the estimated future cash flows based on financial budgets for the next five years. An annual growth rate of 0.4% was applied for the cash flows expected to be incurred after five years and is not expected to exceed the Group’s long-term wireless telecommunication business growth rate. Management of the Group does not expect the total carrying amount of the CGU will exceed the total recoverable amount due to reasonably possible changes from the major assumptions used to estimate the recoverable amount.

(*2) Goodwill related to acquisition of SK Broadband Co., Ltd.

The recoverable amount of the CGU is based on its value in use calculated by applying the annual discount rate of 5.1% to the estimated future cash flows based on financial budgets for the next five years. An annual growth rate of 1.0% was applied for the cash flows expected to be incurred after five years and is not expected to exceed the Group’s long-term wireless telecommunication business growth rate. Management of the Group does not expect the total carrying amount of the CGU will exceed the total recoverable amount due to reasonably possible changes from the major assumptions used to estimate the recoverable amount.

(2) Details of the changes in goodwill for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Beginning balance	￦	1,932,452			1,908,590
Acquisition		35,221			19,974
Impairment loss		(33,441	)		—
Other		(19,215	)		3,888
	￦	1,915,017			1,932,452

Accumulated impairment losses as of December 31, 2017 and 2016 are ￦50,710 million and ￦17,269 million, respectively.

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Intangible Assets

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Intangible Assets

16. Intangible Assets

(1) Intangible assets as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Acquisition cost		Accumulated amortization			Accumulated impairment			Carrying amount
Frequency usage rights	￦	4,843,955		(2,667,015	)		—			2,176,940
Land usage rights		65,841		(50,091	)		—			15,750
Industrial rights		166,082		(54,735	)		—			111,347
Development costs		140,460		(134,828	)		(1,529	)		4,103
Facility usage rights		153,438		(116,987	)		—			36,451
Customer relations		20,796		(16,761	)		—			4,035
Club memberships(*1)		108,382		—			(34,768	)		73,614
Other(*2)		3,911,749		(2,733,485	)		(13,539	)		1,164,725
	￦	9,410,703		(5,773,902	)		(49,836	)		3,586,965

(In millions of won)
	December 31, 2016
	Acquisition cost		Accumulated amortization			Accumulated impairment			Carrying amount
Frequency usage rights	￦	4,843,955		(2,263,127	)		—			2,580,828
Land usage rights		65,148		(44,314	)		—			20,834
Industrial rights		160,897		(39,697	)		—			121,200
Development costs		141,727		(136,446	)		(410	)		4,871
Facility usage rights		151,906		(110,118	)		—			41,788
Customer relations		19,742		(13,090	)		—			6,652
Club memberships(*1)		113,161		—			(39,122	)		74,039
Other(*2)		3,315,921		(2,386,992	)		(2,787	)		926,142
	￦	8,812,457		(4,993,784	)		(42,319	)		3,776,354

(*1) Club memberships are classified as intangible assets with indefinite useful life and are not amortized.

(*2) Other intangible assets primarily consist of computer software and usage rights to a research facility which the Group built and donated, and the Group is given rights-to-use for a definite number of years in turn.

(2) Details of the changes in intangible assets for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017
	Beginning balance		Acquisition		Disposal			Transfer (*1)			Amortization			Impair- ment (*2)			Business combina- tion(*3)		Others			Ending balance
Frequency usage rights	￦	2,580,828		—		—			—			(403,888	)		—			—		—			2,176,940
Land usage rights		20,834		3,689		(972	)		200			(8,001	)		—			—		—			15,750
Industrial rights		121,200		2,677		(28	)		(5,635	)		(6,870	)		—			4		(1	)		111,347
Development costs		4,871		3,813		(9	)		(793	)		(2,660	)		(1,119	)		—		—			4,103
Facility usage rights		41,788		2,805		(36	)		129			(8,235	)		—			—		—			36,451
Customer relations		6,652		1,054		—			—			(3,671	)		—			—		—			4,035
Club memberships		74,039		5,023		(3,452	)		122			—			(769	)		—		(1,349	)		73,614
Other		926,142		127,396		(19,698	)		503,277			(369,546	)		(16,605	)		14,118		(359	)		1,164,725
	￦	3,776,354		146,457		(24,195	)		497,300			(802,871	)		(18,493	)		14,122		(1,709	)		3,586,965

(*1) Includes reclassification from advance payments and property and equipment.

(*2) The Group recognized the difference between recoverable amount and the carrying amount of club memberships amounting to ￦18,493 million as impairment loss for the year ended December 31, 2017.

(*3) Includes intangible assets acquired as a result of IRIVER LIMITED’s purchase and merge of S.M. LIFE DESIGN COMPANY INC. and SM mobile communications Co., Ltd. during the year ended December 31, 2017.

(In millions of won)
	2016
	Beginning balance		Acquisition		Disposal			Transfer (*2)		Amortiza -tion			Impair- ment(*3)			Business combina- tion		Ending balance
Frequency usage rights(*1)	￦	1,103,517		1,810,076		—			—		(332,765	)		—			—		2,580,828
Land usage rights		26,576		5,338		(1,921	)		—		(9,159	)		—			—		20,834
Industrial rights		116,542		6,226		(148	)		5,004		(6,424	)		—			—		121,200
Development costs		7,472		1,404		—			338		(3,933	)		(410	)		—		4,871
Facility usage rights		48,019		2,181		(50	)		231		(8,593	)		—			—		41,788
Customer relations		7,175		499		—			—		(4,051	)		—			3,029		6,652
Club memberships		91,507		7,983		(7,624	)		—		—			(17,827	)		—		74,039
Other		903,976		141,045		(20,306	)		228,110		(323,397	)		(3,286	)		—		926,142
	￦	2,304,784		1,974,752		(30,049	)		233,683		(688,322	)		(21,523	)		3,029		3,776,354

(*1) During the year ended December 31, 2016, the Parent Company acquired the frequency right for bandwidth blocs in the 2.6 GHz band for ￦1,330,100 million at the spectrum auction held by the Ministry of Science, ICT and Future Planning (MSIP) of Korea and made the initial payment in accordance with the terms of the agreement in August 2016. The remaining consideration will be paid on an annual installment basis for 10 years from August 2016. In addition, the Parent Company extended frequency usage rights for 2.1 GHz band for ￦568,500 million with the initial payment made to MSIP during the year ended December 31, 2016. The remaining consideration will be paid on an annual installment basis for 5 years from December 2016.

(*2) Includes reclassification from advance payments and property and equipment.

(*3) The Group recognized the difference between recoverable amount and the carrying amount of intangible assets, amounting to ￦21,523 million as impairment loss for the year ended December 31, 2016.

(3) Research and development expenditures recognized as expense for the years ended December 31, 2017, 2016 and 2015 are as follows:

	2017		2016		2015
Research and development costs expensed as incurred	￦	395,276		344,787		315,790

(4) The carrying amount and residual useful lives of frequency usage rights as of December 31, 2017 are as follows, all of which are amortized on a straight-line basis:

(In millions of won)
	Amount		Description	Commencement of amortization		Completion of amortization
800MHz license	￦	141,904	Frequency usage rights relating to CDMA and LTE service		Jul. 2011		Jun. 2021
1.8GHz license		502,480	Frequency usage rights relating to LTE service		Sept. 2013		Dec. 2021
WiBro license		2,957	WiBro service		Mar. 2012		Mar. 2019
2.6GHz license		1,092,770	Frequency usage rights relating to LTE service		Sept. 2016		Dec. 2026
2.1GHz license		436,829	Frequency usage rights relating to W-CDMA and LTE service		Dec. 2016		Dec. 2021
	￦	2,176,940

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Borrowings and Debentures

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Borrowings and Debentures

17. Borrowings and Debentures

(1) Short-term borrowings as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	Lender		Annual interest rate (%)		December 31, 2017		December 31, 2016
Short-term borrowings		Shinhan Bank		2.85	￦	30,000		—
		Woori Bank		2.88		—		2,614
Commercial paper		KEB Hana Bank		1.67		50,000		—
Bank overdraft		KEB Hana Bank		3.17		30,000		—
		Shinhan Bank		3.38		20,000		—
					￦	130,000		2,614

(2) Long-term borrowings as of December 31, 2017 and 2016 are as follows:

(In millions of won )
Lender	Annual interest rate (%)		Maturity		December 31, 2017			December 31, 2016
Korea Development Bank(*1)		3.20		Mar. 31, 2020	￦	30,000			—
KEB Hana Bank		3.18		Feb. 28, 2019		40,000			—
Kookmin Bank		1.29		Mar. 15, 2017		—			500
Kookmin Bank		1.95		Mar. 15, 2018		717			3,583
Korea Development Bank(*2)		1.99		Jul. 30, 2019		22,750			35,750
Korea Development Bank(*2)		1.99		Jul. 30, 2019		5,833			9,167
Korea Development Bank(*2)		2.27		Dec. 20, 2021		49,000			49,000
Korea Development Bank(*2)		2.37		Dec. 21, 2022		50,000			—
Export Kreditnamnden(*3)		1.70		Apr. 29, 2022		55,471			76,493
						(USD 51,775	)		(USD 63,296	)
Sub-total						253,771			174,493
Less present value discount						(954	)		(1,586	)
						252,817			172,907
Less current portion						(41,331	)		(33,191	)
					￦	211,486			139,716

(*1) SK Planet Co., Ltd., one of the subsidiaries of the Parent Company entered into a floating-to-fixed interest rate swap agreement to hedge the interest rate risk.

(*2) SK Broadband Co., Ltd., one of the subsidiaries of the Parent Company entered into a floating-to-fixed interest rate swap agreement to hedge the interest rate risk.

(*3) The long-term borrowings are to be repaid by installments on an annual basis from 2014 to 2022.

(3) Debentures as of December 31, 2017 and 2016 are as follows:

(In millions of won, thousands of U.S. dollars and thousands of other currencies)
	Purpose	Maturity		Annual interest rate (%)	December 31, 2017		December 31, 2016
Unsecured corporate bonds	Other fund	2018		5.00	￦	200,000		200,000
Unsecured corporate bonds	Operating fund	2021		4.22		190,000		190,000
Unsecured corporate bonds	Operating and refinancing fund	2019		3.24		170,000		170,000
Unsecured corporate bonds		2022		3.30		140,000		140,000
Unsecured corporate bonds		2032		3.45		90,000		90,000
Unsecured corporate bonds	Operating fund	2023		3.03		230,000		230,000
Unsecured corporate bonds		2033		3.22		130,000		130,000
Unsecured corporate bonds		2019		3.30		50,000		50,000
Unsecured corporate bonds		2024		3.64		150,000		150,000
Unsecured corporate bonds(*1)		2029		4.72		60,278		59,600
Unsecured corporate bonds	Refinancing fund	2019		2.53		160,000		160,000
Unsecured corporate bonds		2021		2.66		150,000		150,000
Unsecured corporate bonds		2024		2.82		190,000		190,000
Unsecured corporate bonds	Operating and refinancing fund	2022		2.40		100,000		100,000
Unsecured corporate bonds	refinancing fund	2025		2.49		150,000		150,000
Unsecured corporate bonds		2030		2.61		50,000		50,000
Unsecured corporate bonds	Operating fund	2018		1.89		90,000		90,000
Unsecured corporate bonds		2025		2.66		70,000		70,000
Unsecured corporate bonds		2030		2.82		90,000		90,000
Unsecured corporate bonds	Operating and refinancing fund	2018		2.07		80,000		80,000
Unsecured corporate bonds		2025		2.55		100,000		100,000
Unsecured corporate bonds		2035		2.75		70,000		70,000
Unsecured corporate bonds	Operating fund	2019		1.65		70,000		70,000
Unsecured corporate bonds		2021		1.80		100,000		100,000
Unsecured corporate bonds		2026		2.08		90,000		90,000
Unsecured corporate bonds		2036		2.24		80,000		80,000
Unsecured corporate bonds		2019		1.62		50,000		50,000
Unsecured corporate bonds		2021		1.71		50,000		50,000
Unsecured corporate bonds		2026		1.97		120,000		120,000
Unsecured corporate bonds		2031		2.17		50,000		50,000
Unsecured corporate bonds	Refinancing fund	2020		1.93		60,000		—
Unsecured corporate bonds		2022		2.17		120,000		—
Unsecured corporate bonds		2027		2.55		100,000		—
Unsecured corporate bonds	Operating and refinancing fund	2032		2.65		90,000		—
Unsecured corporate bonds	Operating fund	2020		2.39		100,000		—
Unsecured corporate bonds	Operating and refinancing fund	2022		2.63		80,000		—
Unsecured corporate bonds	Refinancing fund	2027		2.84		100,000		—
Unsecured corporate bonds(*2)	Operating fund	2017		4.28		—		100,000
Unsecured corporate bonds(*2)		2017		3.27		—		120,000
Unsecured corporate bonds(*2)		2019		3.49		210,000		210,000
Unsecured corporate bonds(*2)		2019		2.76		130,000		130,000
Unsecured corporate bonds(*2)		2018		2.23		50,000		50,000
Unsecured corporate bonds(*2)		2020		2.49		160,000		160,000
Unsecured corporate bonds(*2)		2020		2.43		140,000		140,000
Unsecured corporate bonds(*2)		2020		2.18		130,000		130,000
Unsecured corporate bonds(*2)		2019		1.58		50,000		50,000
Unsecured corporate bonds(*2)	Operating and refinancing fund	2021		1.77		120,000		120,000
Unsecured corporate bonds(*2)	Operating fund	2022		2.26		150,000		—
Unsecured corporate bonds(*2)	Refinancing fund		2022			2.34		30,000		—
Unsecured corporate bonds(*2)	Operating and refinancing fund		2022			2.70		140,000		—
Unsecured corporate bonds(*3)	Operating fund		2017			3.48		—		20,000
Convertible bonds(*4)			2019			1.00		5,558		—
Unsecured global bonds			2027			6.63		428,560		483,400
								(USD 400,000	)	(USD 400,000	)
Unsecured private Swiss bonds			2017			1.75		—		354,399
bonds										(CHF 300,000	)
Unsecured global bonds			2018			2.13		749,980		845,950
								(USD 700,000	)	(USD 700,000	)
Unsecured corporate Australian bonds			2017			4.75		—		261,615
										(AUD 300,000	)
Floating rate notes(*5)			2020			3M Libor + 0.88		321,420		362,550
								(USD 300,000)		(USD 300,000	)
Foreign global bonds(*2)			2018			2.88		321,420		362,550
								(USD 300,000	)	(USD 300,000	)
Sub-total								7,107,216		7,220,064
Less discounts on bonds								(21,029	)	(25,858	)
								7,086,187		7,194,206
Less current portion of bonds								(1,489,617	)	(855,276	)
							￦	5,596,570		6,338,930

(*1) The Group eliminated a measurement inconsistency of accounting profit or loss between the bonds and related derivatives by designating the structured bonds as financial liabilities at fair value through profit or loss. The carrying amount of financial liabilities designated at fair value through profit or loss exceeds the principal amount required to pay at maturity by ￦10,278 million as of December 31, 2017.

(*2) Unsecured corporate bonds were issued by SK Broadband Co., Ltd.

(*3) Unsecured corporate bonds were issued by PS&Marketing Corporation.

(*4) During the year ended December 31, 2017, the Parent Company sold the convertible bonds issued by IRIVER LIMITED to third parties.

(*5) As of December 31, 2017, 3M LIBOR rate is 1.69%.

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Long-term Payables - Other

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Long-term Payables - Other

18. Long-term Payables — Other

(1) Long-term payables — other as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Payables related to acquisition of frequency usage rights	￦	1,328,630		1,602,943
Other(*)		18,133		21,647
	￦	1,346,763		1,624,590

(*) Other includes other long-term employee compensation liabilities.

(2) As of December 31, 2017 and 2016, details of long-term payables — other which consist of payables related to the acquisition of frequency usage rights are as follows (See Note 16):

(In millions of won)
	December 31, 2017			December 31, 2016
Long-term payables — other	￦	1,710,255			2,013,122
Present value discount on long-term payables — other		(79,874	)		(108,406	)
		1,630,381			1,904,716
Less current portion of long-term payables — other		(301,751	)		(301,773	)
Carrying amount at December 31	￦	1,328,630			1,602,943

(3) The repayment schedule of the principal amount of long-term payables — other related to acquisition of frequency usage rights as of December 31, 2017 is as follows:

(In millions of won)
	Amount
Less than 1 year	￦	302,867
1~3 years		605,734
3~5 years		402,624
More than 5 years		399,030
	￦	1,710,255

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Provisions

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Provisions

19. Provisions

(1) Changes in provisions for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	For the year ended December 31, 2017														As of December 31, 2017
	Beginning balance		Increase		Utilization			Reversal			Other		Ending balance		Current		Non-current
Provision for installment of handset subsidy(*1)	￦	24,710		2		(8,898	)		(11,940	)		—		3,874		3,874		—
Provision for restoration(*2)		64,679		12,066		(2,517	)		(1,006	)		45		73,267		40,598		32,669
Emission allowance(*3)		2,788		4,663		(518	)		(2,283	)		—		4,650		4,650		—
Other provisions		5,740		952		(3,757	)		—			—		2,935		2,935		—
	￦	97,917		17,683		(15,690	)		(15,229	)		45		84,726		52,057		32,669

(In millions of won)
	For the year ended December 31, 2016														As of December 31, 2016
	Beginning balance		Increase		Utilization			Reversal			Other		Ending balance		Current		Non-current
Provision for installment of handset subsidy(*1)	￦	5,670		37,530		(18,490	)		—			—		24,710		19,939		4,771
Provision for restoration(*2)		59,954		6,677		(1,082	)		(913	)		43		64,679		37,760		26,919
Emission allowance(*3)		1,477		1,480		(169	)		—			—		2,788		2,788		—
Other provisions		3,104		3,237		(601	)		—			—		5,740		5,740		—
	￦	70,205		48,924		(20,342	)		(913	)		43		97,917		66,227		31,690

(*1) The Group recognizes a provision for handset subsidies given to the subscribers who purchase handsets on an installment basis. The amount recognized as a provision for handset subsidies is the Group’s best estimate of the expenditure required to settle the current obligations to the relevant subscribers at the end of the reporting period, which is calculated as of the present values of estimated handset subsidies to be granted over the relevant service periods, taking into account the customer retention rate for the relevant subscribers. The discount rate used in calculating the present values is based on AAA-rated corporate bonds with a two-year maturity. The customer retention rate is based on the Group’s historical retention rate.

(*2) In the course of the Group’s activities, base station and other assets are installed on leased premises which are expected to have costs associated with restoring the premises to their original conditions where these assets are situated upon ceasing their use on those premises. The associated cash outflows, which are long-term in nature, are generally expected to occur at the dates of the termination of lease contracts to which the assets relate. These restoration costs are calculated on the basis of the identified costs for the current financial year, extrapolated into the future based on management’s best estimates of future trends in prices, inflation, and other factors, and are discounted to present value at a risk-adjusted rate specifically applicable to the liability. Forecasts of estimated future cash outflows are revised in light of future changes in business conditions or technological requirements. The Group records these restoration costs as property and equipment and subsequently expenses them using the straight-line method over the asset’s useful life, and records the accretion of the liability as a charge to finance costs.

(*3) The Group recognizes estimated future payment for the number of emission certificates required to settle the Group’s obligation exceeding the actual number of certificates on hand as emission allowances according to the Act on Allocation and Trading of Greenhouse Gas Emission Permits.

(2) The followings are the key assumptions concerning the future, and other key sources of estimation uncertainty at the end of the reporting period.

	Key assumptions
Provision for handset subsidy	estimation based on historical service retention period data
Provision for restoration	estimation based on cost of demolition and inflation with an assumption of demolishing the relevant assets after six years

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Lease

12 Months Ended

Dec. 31, 2017

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Lease

20. Lease

In 2012, the Group disposed a portion of its property and equipment and investment property, and entered into lease agreements with respect to those assets. These sale and leaseback transactions were accounted for as operating leases. The Group entered into operating lease agreements and sublease agreements in relation to rented office space and the expected future lease payments and lease revenues as of December 31, 2017 are as follows:

(In millions of won)
	Minimum lease payments		Revenues
Less than 1 year	￦	49,289		1,926
1~5 years		101,872		916
	￦	151,161		2,842

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Defined Benefit Liabilities(Assets)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Defined Benefit Liabilities(Assets)

21. Defined Benefit Liabilities(Assets)

(1) Details of defined benefit liabilities(assets) as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017			December 31, 2016
Present value of defined benefit obligations	￦	679,625			595,667
Fair value of plan assets		(663,617	)		(555,175	)
Defined benefit assets(*)		(45,952	)		(30,247	)
Defined benefit liabilities		61,960			70,739

(*) Since the Group entities neither have legally enforceable right nor intention to settle the defined benefit obligations of Group entities with defined benefit assets of other Group entities, defined benefit assets of Group entities have been separately presented from defined benefit liabilities.

(2) Principal actuarial assumptions as of December 31, 2017 and 2016 are as follows:

	December 31, 2017	December 31, 2016
Discount rate for defined benefit obligations	2.58%~4.03%	1.90%~2.96%
Expected rate of salary increase	3.08%~5.93%	2.49%~6.09%

Discount rate for defined benefit obligation is determined based on market yields of high-quality corporate bonds with similar maturities for estimated payment term of defined benefit obligation. Expected rate of salary increase is determined based on the Group’s historical promotion index, inflation rate and salary increase ratio.

(3) Changes in defined benefit obligations for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Beginning balance	￦	595,667			525,269
Current service cost		125,526			114,528
Interest cost		15,991			13,441
Remeasurement - Demographic assumption		(287	)		677
- Financial assumption		(20,731	)		(2,462	)
- Adjustment based on experience		11,561			6,229
Benefit paid		(60,883	)		(55,350	)
Others		12,781			(6,665	)
Ending balance	￦	679,625			595,667

(4) Changes in plan assets for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Beginning balance	￦	555,175			426,413
Interest income		13,821			9,826
Remeasurement		(5,540	)		(6,320	)
Contributions		155,834			159,687
Benefit paid		(60,006	)		(34,247	)
Others		4,333			(184	)
Ending balance	￦	663,617			555,175

The Group expects to make a contribution of ￦146,086 million to the defined benefit plans in 2018.

(5) Total amount of expenses recognized in profit and loss (included in labor in the consolidated statement of income) and capitalized into construction-in-progress for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Current service cost	￦	125,526		114,528		106,764
Net interest cost		2,170		3,615		3,257
	￦127,696		118,143		110,021

(6) Details of plan assets as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Equity instruments	￦	15,567		13,640
Debt instruments		134,710		95,359
Short-term financial instruments, etc.		513,340		446,176
	￦	663,617		555,175

(7) As of December 31, 2017, effects on defined benefit obligations if each of significant actuarial assumptions changes within expectable and reasonable range are as follows:

(In millions of won)
	0.5% Increase			0.5% Decrease
Discount rate	￦	(24,702	)		26,808
Expected salary increase rate		26,988			(25,138	)

The sensitivity analysis does not consider dispersion of all cash flows that are expected from the plan and provides approximate values of sensitivity for the assumptions used.

A weighted average duration of defined benefit obligations as of December 31, 2017 is 8.17 years.

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Derivative Instruments

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Derivative Instruments

22. Derivative Instruments

(1) Currency and interest rate swap contracts under cash flow hedge accounting as of December 31, 2017 are as follows:

(In millions of won and thousands of foreign currencies)
Borrowing date	Hedging Instrument(Hedged item)	Hedged risk	Financial institution	Duration of contract
Jul. 20, 2007	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 400,000)	Foreign currency risk	Morgan Stanley and four other banks	Jul. 20, 2007 ~ Jul. 20, 2027
Nov. 1, 2012	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 700,000)	Foreign currency risk	Standard Chartered and eight other banks	Nov. 1, 2012~ May. 1, 2018
Mar. 7, 2013	Floating-to-fixed cross currency interest rate swap (U.S. dollar denominated bonds face value of USD 300,000)	Foreign currency risk and interest rate risk	DBS bank	Mar. 7, 2013 ~ Mar. 7, 2020
Oct. 29, 2013	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 300,000)	Foreign currency risk	Korea Development Bank and others	Oct. 29, 2013 ~ Oct. 26, 2018
Dec. 16, 2013	Fixed-to-fixed cross currency swap (U.S. dollar borrowing amounting to USD 51,775)	Foreign currency risk	Deutsche bank	Dec. 16, 2013 ~ Apr. 29, 2022
Dec. 20, 2016	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 49,000)	Interest rate risk	Korea Development Bank	Dec. 20, 2016~ Dec. 20, 2021
Jan. 30, 2017	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 28,583)	Interest rate risk	Korea Development Bank	Nov. 10, 2016~ Jul. 30, 2019
Mar. 31, 2017	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 30,000)	Interest rate risk	Korea Development Bank	Mar. 31, 2017- Mar. 31, 2020
Dec. 21, 2017	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 50,000)	Interest rate risk	Korea Development Bank	Dec. 5, 2017- Dec. 21, 2022

(2) As of December 31, 2017, details of fair values of the above derivatives recorded in assets or liabilities are as follows:

(In millions of won and thousands of foreign currencies)
Hedging instrument(Hedged item)	Cash flow hedge			Held for trading		Embedded derivatives		Fair value
Non-current assets:
Redeemable convertible preferred shares issued by Bluehole INC.	￦	—			—		222,257		222,257
Structured bond(face value of KRW 50,000)		—			9,054		—		9,054
Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 400,000)		21,554			—		—		21,554
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 49,000)		307			—		—		307
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 28,583)		43			—		—		43
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 50,000)		(2	)		—		—		(2	)
Total assets								￦	253,213
Current liabilities:
Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 700,000)	￦	(27,791	)		—		—		(27,791	)
Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 300,000)		(615	)		—		—		(615	)
Non-current liabilities:
Floating-to-fixed cross currency interest rate swap (U.S. dollar denominated bonds face value of USD 300,000)		(7,613	)		—		—		(7,613	)
Fixed-to-fixed long-term borrowings (U.S. dollar borrowing amounting to USD 51,775)		(3,106	)		—		—		(3,106	)
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 30,000)		(345	)		—		—		(345	)
Total liabilities								￦	(39,470	)

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Share Capital and Capital Surplus (Deficit) and Others

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Share Capital and Capital Surplus (Deficit) and Others

23. Share Capital and Capital Surplus (deficit) and Others

The Parent Company’s outstanding share capital consists entirely of common shares with a par value of ￦500. The number of authorized, issued and outstanding common shares and the details of capital surplus (deficit) and others as of December 31, 2017 and 2016 are as follows:

(In millions of won, except for share data)
	December 31, 2017			December 31, 2016
Number of authorized shares		220,000,000			220,000,000
Number of issued shares(*1)		80,745,711			80,745,711
Share capital
Common share	￦	44,639			44,639
Capital surplus (deficit) and others:
Paid-in surplus		2,915,887			2,915,887
Treasury shares(Note 24)		(2,260,626	)		(2,260,626	)
Share option(Note 26)		414			—
Others(*2)		(857,912	)		(854,000	)
	￦	(202,237	)		(198,739	)

(*1) In 2002 and 2003, the Parent Company retired treasury shares with reduction of retained earnings before appropriation. As a result, the Parent Company’s outstanding shares have decreased without change in share capital.

(*2) Others primarily consist of the excess of the consideration paid by the Group over the carrying values of net assets acquired from entities under common control.

There were no changes in share capital during the years ended December 31, 2017 and 2016 and details of shares outstanding as of December 31, 2017 and 2016 are as follows:

(In shares)	2017						2016
	Issued shares		Treasury shares		Outstanding shares		Issued shares		Treasury shares		Outstanding shares
Shares outstanding		80,745,711		10,136,551		70,609,160		80,745,711		10,136,551		70,609,160

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Treasury Shares

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Treasury Shares

24. Treasury Shares

The Parent Company acquired treasury shares to provide share dividends, merge with Shinsegi Telecom, Inc. and SK IMT Co, Ltd., increase shareholder value and stabilize its share prices.

Treasury shares as of December 31, 2017 and 2016 are as follows:

(In millions of won, shares)
	December 31, 2017		December 31, 2016
Number of shares		10,136,551		10,136,551
Acquisition cost	￦	2,260,626		2,260,626

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Hybrid Bonds

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Hybrid Bonds

25. Hybrid Bonds

Hybrid bonds classified as equity as of December 31, 2017 are as follows:

(In millions of won)
	Type	Issuance date	Maturity(*1)	Annual interest rate(%)(*2)		Amount
Private hybrid bonds	Unsecured subordinated bearer bond	June 7, 2013	June 7, 2073		4.21	￦	400,000
Issuance costs							(1,482	)
						￦	398,518

Hybrid bonds issued by the Parent Company are classified as equity as there is no contractual obligation for delivery of financial assets to the bond holders. These are subordinated bonds which rank before common shares in the event of a liquidation or reorganization of the Parent Company.

(*1) The Parent Company has a right to extend the maturity under the same terms at issuance without any notice or announcement. The Parent Company also has the right to defer interest payment at its sole discretion.

(*2) Annual interest rate is calculated as yield rate of 5 year national bonds plus premium. According to the step-up clause, additional premium of 0.25% and 0.75%, respectively, after 10 years and 25 years from the issuance date are applied.

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Share option

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Share option

26. Share option

(1) At the shareholders’ meeting held on March 24, 2017, the Parent Company established a share option program that entitles key management personnel the option to purchase common shares of the Parent Company. The terms and conditions related to the grants of the share options under the share option program are as follows:

	Series
	1-1	1-2	1-3
Grant date	March 24, 2017
Types of shares to be issued	66,504 of registered common shares
Grant method	Reissue of treasury shares
Number of shares (in shares)	22,168	22,168	22,168
Exercise price (in won)	246,750	266,490	287,810
Exercise period	Mar. 25, 2019 ~ Mar. 24, 2022	Mar. 25, 2020 ~ Mar. 24, 2023	Mar. 25, 2021 ~ Mar. 24, 2024
Vesting conditions	2 years’ service from the grant date	3 years’ service from the grant date	4 years’ service from the grant date

(2) Share compensation expense recognized during the year ended December 31, 2017 and the remaining share compensation expense to be recognized in subsequent periods are as follows:

(In millions of won)	Share compensation expense
During the year ended December 31, 2017	￦	414
In subsequent periods		977
	￦	1,391

(3) The Group used binomial option pricing model in the measurement of the fair value of the share options at grant date and the inputs used in the model are as follows:

	1-1			1-2			1-3
Risk-free interest rate		1.86	%		1.95	%		2.07	%
Estimated option’s life		5 years			6 years			7 years
Share price (Closing price on the preceding day in won)		262,500			262,500			262,500
Expected volatility		13.38	%		13.38	%		13.38	%
Expected dividends		3.80	%		3.80	%		3.80	%
Exercise price (in won)		246,750			266,490			287,810
Per share fair value of the option (in won)		27,015			20,240			15,480

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Retained Earnings

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Retained Earnings

27. Retained Earnings

(1) Retained earnings as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Appropriated:
Legal reserve	￦	22,320		22,320
Reserve for research & manpower development		—		60,001
Reserve for business expansion		10,171,138		9,871,138
Reserve for technology development		3,071,300		2,826,300
		13,264,758		12,779,759
Unappropriated		4,571,188		3,173,405
	￦	17,835,946		15,953,164

(2) Legal reserve

The Korean Commercial Act requires the Parent Company to appropriate as a legal reserve at least 10% of cash dividends paid for each accounting period until the reserve equals 50% of outstanding share capital. The legal reserve may not be utilized for cash dividends, but may only be used to offset a future deficit, if any, or may be transferred to share capital.

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Reserves

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Reserves

28. Reserves

(1) Details of reserves, net of taxes, as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017			December 31, 2016
Valuation gain on available-for-sale financial assets	￦	168,211			12,534
Other comprehensive loss of investments in associates		(320,060	)		(179,167	)
Valuation loss on derivatives		(73,828	)		(96,418	)
Foreign currency translation differences for foreign operations		(9,050	)		36,868
	￦	(234,727	)		(226,183	)

(2) Changes in reserves for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)	2017
	Valuation gain on available-for-sale financial assets		Other compre- hensive loss of investments in associates			Valuation gain (loss) on derivatives			Foreign currency translation differences for foreign operations			Total
Balance at January 1, 2017	￦	12,534		(179,167	)		(96,418	)		36,868			(226,183	)
Changes, net of taxes		155,677		(140,893	)		22,590			(45,918	)		(8,544	)
Balance at December 31, 2017	￦	168,211		(320,060	)		(73,828	)		(9,050	)		(234,727	)

(In millions of won)
	2016
	Valuation gain (loss) on available-for-sale financial assets			Other compre- hensive loss of investments in associates			Valuation loss on derivatives			Foreign currency translation differences for foreign operations		Total
Balance at January 1, 2016	￦	232,316			(169,520	)		(83,200	)		29,707		9,303
Changes, net of taxes		(219,782	)		(9,647	)		(13,218	)		7,161		(235,486	)
Balance at December 31, 2016	￦	12,534			(179,167	)		(96,418	)		36,868		(226,183	)

(3) Changes in valuation gain on available-for-sale financial assets for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017		2016
Balance at January 1	￦	12,534		232,316
Amount recognized as other comprehensive income during the year, net of taxes		132,586		4,606
Amount reclassified through profit or loss, net of taxes 23,091		23,091		(224,388	)
Balance at December 31	￦	168,211		12,534

(4) Changes in valuation gain (loss) on derivatives for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Balance at January 1	￦	(96,418	)		(83,200	)
Amount recognized as other comprehensive loss during the year, net of taxes		17,965			(12,213	)
Amount reclassified through profit or loss, net of taxes		4,625			(1,005	)
Balance at December 31	￦	(73,828	)		(96,418	)

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Other Operating Income and Expenses

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Other Operating Income and Expenses

29. Other Operating Income and Expenses

Details of other operating income andexpenses for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Other Operating Income:
Gain on disposal of property and equipment and intangible assets		13,991		6,908		7,140
Others(*)		18,006		59,640		23,795
	￦	31,997		66,548		30,935
Other Operating Expenses:
Communication	￦	27,973		31,196		43,979
Utilities		299,825		277,497		270,621
Taxes and dues		27,819		35,020		36,118
Repair		333,101		326,076		312,517
Research and development		395,276		344,787		315,790
Training		32,853		33,303		37,278
Bad debt for accounts receivable — trade		34,584		37,820		60,450
Travel		24,095		25,263		27,860
Supplies and other		111,170		113,930		176,248
Loss on disposal of property and equipment and intangible assets		60,086		63,797		21,392
Impairment loss on other investment securities		9,003		24,033		42,966
Impairment loss on property and equipment and intangible assets		54,946		24,506		35,845
Donations		112,634		96,633		72,454
Bad debt for accounts receivable — other		5,793		40,312		15,323
Others(*)		101,589		49,593		55,536
	￦	1,630,747		1,523,766		1,524,377

(*) See Note 5-(2).

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Finance Income and Costs

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Finance Income and Costs

30. Finance Income and Costs

(1) Details of finance income and costs for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Finance Income:
Interest income	￦	76,045		54,353		45,884
Gain on sale of accounts receivable — trade		18,548		18,638		—
Dividends		12,416		19,161		16,102
Gain on foreign currency transactions		13,676		14,186		18,923
Gain on foreign currency translations		7,110		5,085		5,090
Gain on disposal of long-term investment securities		4,890		459,349		10,786
Gain on valuation of derivatives		223,943		4,132		1,927
Reversal of impairment loss on available-for-sale financial assets		9,900		—		—
Gain relating to financial assets at fair value through profit or loss		33		25		—
Gain relating to financial liability at fair value through profit or loss		—		121		5,188
	￦	366,561		575,050		103,900
Finance Costs:
Interest expense	￦	299,100		290,454		297,662
Loss on sale of accounts receivable — trade		9,682		—		—
Loss on foreign currency transactions		19,263		16,765		17,931
Loss on foreign currency translations		8,419		3,991		4,750
Loss on disposal of long-term investment securities		36,024		2,919		2,599
Loss on settlement of derivatives		10,031		3,428		4,845
Loss relating to financial liability at fair value through profit or loss		678		4,018		526
Impairment loss on long-term investment securities(*)		14,519		5,255		21,787
Other finance costs		35,900		—		—
	￦	433,616		326,830		350,100

(*) See Note 30-(5).

(2) Details of interest income included in finance income for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Interest income on cash equivalents and short-term financial instruments	￦	28,130		20,203		20,009
Interest income on installment receivables and others		47,915		34,150		25,875
	￦	76,045		54,353		45,884

(3) Details of interest expenses included in finance costs for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Interest expense on borrowings	￦	11,774		7,962		19,577
Interest expense on debentures		228,568		239,560		238,450
Interest on finance lease liabilities		—		—		58
Others		58,758		42,932		39,577
	￦	299,100		290,454		297,662

(4) Finance income and costs by category of financial instruments for the years ended December 31, 2017, 2016 and 2015 are as follows. Bad debt expense (reversal of allowance for doubtful accounts) for accounts receivable — trade, loans and receivables are presented and explained separately in Note 7.

(i)    Finance income

(In millions of won)
	2017		2016		2015
Financial Assets:
Financial assets at fair value through profit or loss	￦	223,976		4,157		1,927
Available-for-sale financial assets		30,598		484,300		31,220
Loans and receivables		111,677		86,256		64,749
Sub-total		366,251		574,713		97,896
Financial Liabilities:
Financial liabilities at fair value through profit or loss		—		121		5,188
Financial liabilities measured at amortized cost		310		216		816
Sub-total		310		337		6,004
	￦	366,561		575,050		103,900

(ii)    Finance costs

(In millions of won)
	2017		2016		2015
Financial Assets:
Financial assets at fair value through profit or loss	￦	—		2,791		4,188
Available-for-sale financial assets		86,445		8,174		24,386
Loans and receivables		37,040		15,810		15,861
Derivatives designated as hedging instruments		—		637		657
Sub-total		123,485		27,412		45,092
Financial Liabilities:
Financial liabilities at fair value through profit or loss		678		4,018		526
Financial liabilities measured at amortized cost		299,422		295,400		304,482
Derivatives designated as hedging instruments		10,031		—		—
Sub-total		310,131		299,418		305,008
	￦	433,616		326,830		350,100

(iii)    Other comprehensive income (loss)

(In millions of won)
	2017		2016			2015
Financial Assets:
Available-for-sale financial assets	￦	158,440		(223,981	)		(3,661	)
Derivatives designated as hedging instruments		1,554		(172	)		(3,248	)
Sub-total		159,994		(224,153	)		(6,909	)
Financial Liabilities:
Derivatives designated as hedging instruments		21,032		(13,046	)		1,977
Sub-total		21,032		(13,046	)		1,977
	￦	181,026		(237,199	)		(4,932	)

(5) Details of impairment losses for financial assets for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Available-for-sale financial assets(*)	￦	14,519		5,255		21,787
Accounts receivable — trade		34,584		37,820		60,450
Other receivables		5,793		40,312		15,323
	￦	54,896		83,387		97,560

(*) This is included in other finance costs (See Note 30-(1)).

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Income Tax Expense

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Income Tax Expense

31. Income Tax Expense

(1) Income tax expenses for the years ended December 31, 2017, 2016 and 2015 consist of the following:

(In millions of won)
	2017			2016			2015
Current tax expense
Current year	￦	424,773			473,543			417,022
Current tax of prior years(*)		(105,158	)		(11,925	)		(4,124	)
		319,615			461,618			412,898
Deferred tax expense
Changes in net deferred tax assets		426,039			(25,580	)		106,399
Others (tax rate differences, etc.)		—			—			183
Income tax expense	￦	745,654			436,038			519,480

(*) Current tax of prior years are mainly composed of the income tax refund due to a change in the interpretation of the tax authority in relation to the income tax previously recognized by the Group.

(2) The difference between income taxes computed using the statutory corporate income tax rates and the recorded income taxes for the years ended December 31, 2017, 2016 and 2015 is attributable to the following:

(In millions of won)
	2017			2016			2015
Income taxes at statutory income tax rate	￦	823,124			506,804			492,096
Non-taxable income		(40,080	)		(38,989	)		(85,589	)
Non-deductible expenses		31,285			52,648			44,770
Tax credit and tax reduction		(34,300	)		(29,484	)		(25,756	)
Changes in unrecognized deferred taxes		31,857			(84,276	)		83,623
Others (income tax refund, etc.)(*)		(66,232	)		29,335			10,336
Income tax expense	￦	745,654			436,038			519,480

(*) Based on the amendment to Korean Tax Law that was enacted in 2017, the income tax rate for taxable income in excess of ￦300,000 million is changed from 24.2% to 27.5%, which will be effective from January 1, 2018. The Group remeasured deferred tax assets and liabilities as a result of this rate change.

Tax rates applied for the above taxable income for the years ended December 31, 2017, 2016 and 2015 are corporate income tax rates applied to taxable income in the Republic of Korea, in which the Parent Company is located.

(3) Deferred taxes directly charged to (credited from) equity for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017			2016		2015
Valuation gain (loss) on available-for-sale financial assets	￦	(55,883	)		82,993		2,461
Share of other comprehensive income (loss) of associates		(260	)		2		(63	)
Valuation gain (loss) on derivatives		(3,019	)		4,454		(448	)
Remeasurement of defined benefit liabilities		1,618			3,174		2,719
	￦	(57,544	)		90,623		4,669

(4) Details of the changes in deferred tax assets (liabilities) for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017
	Beginning			Deferred tax expense (income)			Directly charged to (credited from) equity			Others			Ending
Deferred tax assets (liabilities) related to temporary differences:
Allowance for doubtful accounts	￦	61,911			5,091			—			—			67,002
Accrued interest income		(616	)		(1,851	)		—			—			(2,467	)
Available-for-sale financial assets		101,472			8,192			(55,883	)		—			53,781
Investments in subsidiaries, associates and joint ventures		(476,098	)		(461,271	)		(260	)		—			(937,629	)
Property and equipment (depreciation)		(253,323	)		17,980			—			—			(235,343	)
Provisions		7,448			(5,136	)		—			—			2,312
Retirement benefit obligation		35,505			1,237			1,618			—			38,360
Valuation gain on derivatives		28,975			—			(3,019	)		—			25,956
Gain or loss on foreign currency translation		19,369			2,562			—			—			21,931
Reserve for research and manpower development		(4,775	)		2,388			—			—			(2,387	)
Goodwill		3,105			(938	)		—			—			2,167
Others		34,911			(29,248	)		—			(2,324	)		3,339
		(442,116	)		(460,994	)		(57,544	)		(2,324	)		(962,978	)
Deferred tax assets related to unused tax loss carryforwards and tax credit carryforwards
Tax loss carryforwards		37,462			34,955			—			—			72,417
	￦	(404,654	)		(426,039	)		(57,544	)		(2,324	)		(890,561	)

(In millions of won)
	2016
	Beginning			Deferred tax expense (income)			Directly charged to (credited from) equity		Ending
Deferred tax assets (liabilities) related to temporary differences:
Allowance for doubtful accounts	￦	59,957			1,954			—		61,911
Accrued interest income		(2,567	)		1,951			—		(616	)
Available-for-sale financial assets		30,365			(11,886	)		82,993		101,472
Investments in subsidiaries, associates and joint ventures		(355,273	)		(120,827	)		2		(476,098	)
Property and equipment (depreciation)		(327,572	)		74,249			—		(253,323	)
Provisions		2,485			4,963			—		7,448
Retirement benefit obligation		28,327			4,004			3,174		35,505
Valuation gain on derivatives		24,521			—			4,454		28,975
Gain or loss on foreign currency translation		19,517			(148	)		—		19,369
Reserve for research and manpower development		(7,162	)		2,387			—		(4,775	)
Goodwill		3,713			(608	)		—		3,105
Unearned revenue (activation fees)		2,065			(2,065	)		—		—
Others		(23,782	)		58,693			—		34,911
		(545,406	)		12,667			90,623		(442,116	)
Deferred tax assets related to unused tax loss carryforwards and tax credit carryforwards
Tax loss carryforwards		24,549			12,913			—		37,462
	￦	(520,857	)		25,580			90,623		(404,654	)

(5) Details of temporary differences, unused tax loss carryforwards and unused tax credits carryforwards which are not recognized as deferred tax assets, in the consolidated statements of financial position as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Allowance for doubtful accounts	￦	88,521		165,935
Investments in subsidiaries, associates and joint ventures		168,268		228,025
Other temporary differences		425,653		320,260
Unused tax loss carryforwards		921,309		755,050
Unused tax credit carryforwards		4,092		1,211

(6) The amount of unused tax loss carryforwards and unused tax credit carryforwards which are not recognized as deferred tax assets as of December 31, 2017 are expiring within:

(In millions of won)
	Unused tax loss carryforwards		Unused tax credit carryforwards
Less than 1 year	￦	—		869
1 ~ 2 years		7,686		101
2 ~ 3 years		358,237		119
More than 3 years		555,386		3,003
	￦	921,309		4,092

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Earnings per Share

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Earnings per Share

32. Earnings per Share

(1)     Basic earnings per share

1) Basic earnings per share for the years ended December 31, 2017, 2016 and 2015 are calculated as follows:

(In millions of won, shares)
	2017			2016			2015
Basic earnings per share attributable to owners of the Parent Company:
Profit attributable to owners of the Parent Company	￦	2,599,829			1,675,967			1,518,604
Interest on hybrid bonds		(16,840	)		(16,840	)		(16,840	)
Profit attributable to owners of the Parent Company on common shares		2,582,989			1,659,127			1,501,764
Weighted average number of common shares outstanding		70,609,160			70,609,160			71,551,966
Basic earnings per share (in won)	￦	36,582			23,497			20,988

2) The weighted average number of common shares outstanding for the years ended December 31, 2017, 2016 and 2015 are calculated as follows:

(In shares)
	2017			2016			2015
Issued common shares at January 1		80,745,711			80,745,711			80,745,711
Effect of treasury shares		(10,136,551	)		(10,136,551	)		(9,193,745	)
Weighted average number of common shares outstanding at December 31		70,609,160			70,609,160			71,551,966

(2)    Diluted earnings per share

For the years ended December 31, 2017, 2016 and 2015, diluted earnings per share are the same as basic earnings per share as there are no dilutive potential common shares.

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Dividends

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Dividends

33.    Dividends

(1)    Details of dividends declared

Details of dividend declared for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won, except for face value and share data)
Year	Dividend type	Number of shares outstanding		Face value (in won)		Dividend ratio			Dividends
2017	Cash dividends (Interim)		70,609,160		500		200	%	￦	70,609
	Cash dividends (Year-end)		70,609,160		500		1,800	%		635,482
									￦	706,091
2016	Cash dividends (Interim)		70,609,160		500		200	%	￦	70,609
	Cash dividends (Year-end)		70,609,160		500		1,800	%		635,482
									￦	706,091
2015	Cash dividends (Interim)		72,629,160		500		200	%	￦	72,629
	Cash dividends (Year-end)		70,609,160		500		1,800	%		635,482
									￦	708,111

(2)    Dividends yield ratio

Dividends yield ratios for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In won)
Year	Dividend type	Dividend per share	Closing price at year-end	Dividend yield ratio
2017	Cash dividends	10,000	267,000	3.75%
2016	Cash dividends	10,000	224,000	4.46%
2015	Cash dividends	10,000	215,500	4.64%

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Categories of Financial Instruments

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Categories of Financial Instruments

34.    Categories of Financial Instruments

(1) Financial assets by category as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Financial assets at fair value through profit or loss		Available- for-sale financial assets		Loans and receivables		Derivatives hedging instrument		Total
Cash and cash equivalents	￦	—		—		1,457,735		—		1,457,735
Financial instruments		—		—		618,002		—		618,002
Short-term investment securities		97,003		47,383		—		—		144,386
Long-term investment securities		—		887,007		—		—		887,007
Accounts receivable — trade		—		—		2,138,755		—		2,138,755
Loans and other receivables(*)		—		—		1,962,083		—		1,962,083
Derivative financial assets		231,311		—		—		21,902		253,213
	￦	328,314		934,390		6,176,575		21,902		7,461,181

(In millions of won)
	December 31, 2016
	Financial assets at fair value through profit or loss		Available- for-sale financial assets		Loans and receivables		Derivatives hedging instrument		Total
Cash and cash equivalents	￦	—		—		1,505,242		—		1,505,242
Financial instruments		—		—		469,705		—		469,705
Short-term investment securities		—		107,364		—		—		107,364
Long-term investment securities		—		828,521		—		—		828,521
Accounts receivable — trade		—		—		2,261,311		—		2,261,311
Loans and other receivables(*)		—		—		1,701,249		—		1,701,249
Derivative financial assets		7,368		—		—		207,402		214,770
	￦	7,368		935,885		5,937,507		207,402		7,088,162

(*) Details of loans and other receivables as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Short-term loans	￦	62,830		58,979
Accounts receivable — other		1,260,835		1,121,444
Accrued income		3,979		2,780
Other current assets		3,927		3,937
Long-term loans		50,874		65,476
Long-term accounts receivable — other		287,048		149,669
Guarantee deposits		292,590		298,964
	￦	1,962,083		1,701,249

(2) Financial liabilities by category as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Financial liabilities at fair value through profit or loss		Financial liabilities measured at amortized cost		Derivatives hedging instrument		Total
Accounts payable — trade	￦	—		351,711		—		351,711
Derivative financial liabilities		—		—		39,470		39,470
Borrowings		—		382,817		—		382,817
Debentures(*1)		60,278		7,025,909		—		7,086,187
Accounts payable — other and others(*2)		—		4,865,519		—		4,865,519
	￦	60,278		12,625,956		39,470		12,725,704

(In millions of won)
	December 31, 2016
	Financial liabilities at fair value through profit or loss		Financial liabilities measured at amortized cost		Derivatives hedging instrument		Total
Accounts payable — trade	￦	—		402,445		—		402,445
Derivative financial liabilities		—		—		87,153		87,153
Borrowings		—		175,521		—		175,521
Debentures(*1)		59,600		7,134,606		—		7,194,206
Accounts payable — other and others (*2)		—		4,842,734		—		4,842,734
	￦	59,600		12,555,306		87,153		12,702,059

(*1) Bonds classified as financial liabilities at fair value through profit or loss as of December 31, 2017 and 2016 are structured bonds and they were designated as financial liabilities at fair value through profit or loss in order to eliminate a measurement inconsistency with the related derivatives.

(*2) Details of accounts payable — other and others as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Accounts payable — other	￦	1,867,074		1,767,799
Withholdings		1,736		1,525
Accrued expenses		1,327,906		1,125,816
Current portion of long-term payables — other		302,703		301,773
Long-term payables — other		1,346,763		1,624,590
Other non-current liabilities		19,337		21,231
	￦	4,865,519		4,842,734

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Financial Risk Management

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Financial Risk Management

35. Financial Risk Management

(1) Financial risk management

The Group is exposed to credit risk, liquidity risk and market risk. Market risk is the risk related to the changes in market prices, such as foreign exchange rates, interest rates and equity prices. The Group implements a risk management system to monitor and manage these specific risks.

The Group’s financial assets consist of cash and cash equivalents, financial instruments, available-for-sale financial assets, accounts receivable — trade and other. Financial liabilities consist of accounts payable — trade and other, borrowings, and debentures.

1) Market risk

(i)     Currency risk

The Group incurs exchange position due to revenue and expenses from its global operations. Major foreign currencies where the currency risk occur are USD, JPY and EUR. The Group determines the currency risk management policy after considering the nature of business and the presence of methods that mitigate the currency risk for each Group entities. Currency risk occurs on forecasted transactions and recognized assets and liabilities which are denominated in a currency other than the functional currency of each Group entity. The Group manages currency risk arising from business transactions by using currency forwards, etc.

Monetary assets and liabilities denominated in foreign currencies as of December 31, 2017 are as follows:

(In millions of won, thousands of foreign currencies)
	Assets				Liabilities
	Foreign currencies		Won equivalent		Foreign currencies		Won equivalent
USD		124,901	￦	133,836		1,817,808	￦	1,947,599
EUR		15,669		20,044		63		80
JPY		596,059		5,658		169,729		1,611
Others		—		530		—		195
			￦	160,068			￦	1,949,485

In addition, the Group has entered into cross currency swaps to hedge against currency risk related to foreign currency borrowings and debentures. (Refer to Note 22)

As of December 31, 2017, a hypothetical change in exchange rates by 10% would have increase (reduce) the Group’s income before income tax as follows:

(In millions of won)
	If increased by 10%		If decreased by 10%
USD	￦	5,590		(5,590	)
EUR		1,997		(1,997	)
JPY		405		(405	)
Others		34		(34	)
	￦	8,026		(8,026	)

(ii)    Equity price risk

The Group has listed and non-listed equity securities for its liquidity management and operating purpose. As of December 31, 2017, available-for-sale equity instruments measured at fair value amount to ￦734,487 million.

(iii)    Interest rate risk

The interest rate risk of the Group arises from borrowings and debenture. Since the Group’s interest bearing assets are mostly fixed-interest bearing assets, the Group’s revenue and operating cash flows are not influenced by the changes in market interest rates.

Accordingly, the Group performs various analysis to reduce interest rate risk and to optimize its financing. To minimize risks arising from changes in interest rates, the Group takes various measures such as refinancing, renewal, alternative financing and hedging.

As of December 31, 2017, the floating-rate borrowings and bonds of the Group are ￦228,300 million and ￦321,420 million, respectively, and the Group has entered into interest rate swap agreements, as described in Note 22, for all floating-rate borrowings and debentures to hedge interest rate risk.

If the interest rate increases (decreases) 1% with all other variables held constant, income before income taxes for the year ended December 31, 2017, would change by ￦707 million in relation to floating-rate borrowings that are exposed to interest rate risk.

2) Credit risk

The maximum credit exposure as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017		2016
Cash and cash equivalents	￦	1,457,416		1,505,082
Financial instruments		618,002		469,705
Available-for-sale financial assets		19,928		6,755
Accounts receivable — trade		2,138,755		2,261,311
Loans and other receivables		1,962,083		1,701,249
Derivative financial assets		30,956		214,770
	￦	6,227,140		6,158,872

Credit risk is the risk of financial loss to the Group if a customer or counterparty to a financial instrument fails to meet his/her contractual obligations.

To manage credit risk, the Group evaluates the credit worthiness of each customer or counterparty considering the party’s financial information, its own trading records and other factors. Based on such information, the Group establishes credit limits for each customer or counterparty.

The Group establishes an allowance for doubtful account that represents its estimate of incurred losses in respect of trade and other receivables. The main components of this allowance are a specific loss component that relates to individually significant exposures, and a collective loss component established for groups of similar assets in respect of losses that have been incurred but not yet identified. The collective loss allowance is determined based on historical data of payment statistics for similar financial assets. Also, the Group’s credit risk can arise due to transactions with financial institutions related to its cash and cash equivalents, financial instruments and derivatives. To minimize such risk, the Group has a policy to deal only with financial institutions with high credit ratings. The amount of maximum exposure to credit risk of the Group is the carrying amount of financial assets as of December 31, 2017.

3) Liquidity risk

The Group’s approach to managing liquidity is to ensure that it will always maintain sufficient cash and cash equivalents balances and have enough liquidity through various committed credit lines. The Group maintains enough liquidity within credit lines through active operating activities.

Contractual maturities of financial liabilities as of December 31, 2017 are as follows:

(In millions of won)
	Carrying amount		Contractual cash flows		Less than 1 year		1 - 5 years		More than 5 years
Accounts payable — trade	￦	351,711		351,711		351,711		—		—
Borrowings(*1)		382,817		397,776		177,910		219,866		—
Debentures(*1)		7,086,187		8,230,952		1,682,206		3,675,178		2,873,568
Accounts payable — other and others(*2)		4,865,519		5,030,105		3,519,489		1,093,611		417,005
	￦	12,686,234		14,010,544		5,731,316		4,988,655		3,290,573

The Group does not expect that the cash flows included in the maturity analysis could occur significantly earlier or at different amounts.

(*1) Includes interest payables.

(*2) The Group provides with USD 12,240,000 of payment guarantees for Celcom Planet, one of the joint ventures of the Group, in relation to its borrowings. The contractual cash flows for accounts payable — other and others include the maximum amount that the Group is required to pay in connection with the guarantees.

As of December 31, 2017, periods in which cash flows from cash flow hedge derivatives are expected to occur are as follows:

(In millions of won)
	Carrying amount			Contractual cash flows			Less than 1 year			1 - 5 years			More than 5 years
Assets	￦	21,902			17,118			7,446			28,075			(18,403	)
Liabilities		(39,470	)		(40,220	)		(28,960	)		(11,260	)		—
	￦	(17,568)			(23,102)			(21,514	)		16,815			(18,403	)

(2) Capital management

The Group manages its capital to ensure that it will be able to continue as a business while maximizing the return to shareholders through the optimization of its debt and equity structure. The overall strategy of the Group is the same as that of the Group as of and for the year ended December 31, 2016.

The Group monitors its debt-equity ratio as a capital management indicator. This ratio is calculated as total liabilities divided by total equity; both are from the consolidated financial statements.

Debt-equity ratio as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017			December 31, 2016
Total liabilities	￦	15,399,474			15,181,233
Total equity		18,029,195			16,116,430
Debt-equity ratios		85.41	%		94.20	%

(3) Fair value

1) Fair value and carrying amount of financial assets and liabilities including fair value hierarchy as of December 31, 2017 are as follows:

(In millions of won)
	December 31, 2017
	Carrying amount		Level 1		Level 2		Level 3		Total
Financial assets that are measured at fair value
Financial assets at fair value through profit or loss	￦	328,314		—		106,057		222,257		328,314
Derivative financial assets		21,902		—		21,902		—		21,902
Available-for-sale financial assets		734,487		589,202		47,383		97,902		734,487
	￦	1,084,703		589,202		175,342		320,159		1,084,703
Financial liabilities that are measured at fair value
Financial liabilities at fair value through profit or loss	￦	60,278		—		60,278		—		60,278
Derivative financial liabilities		39,470		—		39,470		—		39,470
	￦	99,748		—		99,748		—		99,748
Financial liabilities that are not measured at fair value
Borrowings	￦	382,817		—		383,748		—		383,748
Debentures		7,025,909		—		7,325,370		—		7,325,370
Long-term payables — other		1,649,466		—		1,766,451		—		1,766,451
	￦	9,058,192		—		9,475,569		—		9,475,569

2) Fair value and carrying amount of financial assets and liabilities including fair value hierarchy as of December 31, 2016 are as follows:

(In millions of won)
	December 31, 2016
	Carrying amount		Level 1		Level 2		Level 3		Total
Financial assets that are measured at fair value:
Financial assets at fair value through profit or loss	￦	7,368		—		7,368		—		7,368
Derivative financial assets		207,402		—		207,402		—		207,402
Available-for-sale financial assets		741,285		526,363		107,364		107,558		741,285
	￦	956,055		526,363		322,134		107,558		956,055
Financial liabilities that are measured at fair value:
Financial liabilities at fair value through profit or loss	￦	59,600		—		59,600		—		59,600
Derivative financial liabilities		87,153		—		87,153		—		87,153
	￦	146,753		—		146,753		—		146,753
Financial liabilities that are not measured at fair value:
Borrowings	￦	175,521		—		177,600		—		177,600
Debentures		7,134,606		—		7,568,361		—		7,568,361
Long-term payables — other		1,926,363		—		2,103,788		—		2,103,788
	￦	9,236,490		—		9,849,749		—		9,849,749

The above information does not include fair values of financial assets and liabilities of which fair values have not been measured as carrying amounts are reasonable approximation of fair values.

Available-for-sale financial assets amounting to ￦199,903 million and ￦194,600 million as of December 31, 2017 and December 31, 2016, respectively, are measured at cost in accordance with IAS 39 since they are equity instruments which do not have quoted price in an active market for the identical instruments and for which fair value cannot be reliably measured using other valuation methods.

Fair value of the financial instruments that are traded in an active market (available-for-sale financial assets, financial liabilities at fair value through profit or loss, etc.) is measured based on the bid price at the end of the reporting date.

The Group uses various valuation methods for determination of fair value of financial instruments that are not traded in an active market. Fair value of available-for-sale securities is determined using the market approach methods and financial assets through profit or loss are measured using the option pricing model. In addition, derivative financial contracts and long-term liabilities are measured using the discounted present value methods. Inputs used to such valuation methods include swap rate, interest rate, and risk premium, and the Group performs valuation using the inputs which are consistent with natures of assets and liabilities measured.

Interest rates used by the Group for the fair value measurement as of December 31, 2017 are as follows:

	Interest rate
Derivative instruments		1.54% ~ 2.67%
Borrowings and debentures		2.48% ~ 2.55%
Long-term payables — other		2.23% ~ 2.60%

3) There have been no transfers from Level 2 to Level 1 in 2017 and changes of financial assets classified as Level 3 for the year ended December 31, 2017 are as follows:

(In millions of won)
	Balance at beginning		Valuation		Transfer		Other compre- hensive loss			Disposal			Balance at ending
Financial assets at fair value through profit or loss(*)	￦	—		222,257		—		—			—			222,257
Available-for-sale financial assets		107,558		—		3,938		(8,942	)		(4,652	)		97,902

(*) The Group holds redeemable convertible preferred shares issued by Bluehole INC. The conversion rights attached to the investments are bifurcated from the host contract as embedded derivatives and the Group recognized ￦222,257 million as financial assets at FVTPL and gain on valuation of derivatives, respectively, as of and during the year ended December 31, 2017. The host contract was recognized as available-for-sale financial assets of ￦15,342 million measured by discounting the amount of collection at maturity including the principal, guaranteed interests, and dividend. The fair value of the conversion rights were measured using the binomial option pricing model by considering inputs such as expected volatility, exercise price, and common share price.

The major inputs used and their correlations with the fair value measurements are as follows.

Significant non-observable inputs	Correlations between inputs and fair value measurements
Value of common shares	If the value of common share increases (decreases), Fair value will increase (decrease)
Exercise price	If the exercise price increases (decreases), Fair value will decrease (increase)
Discount rate	If the discount rate increases (decreases), Fair value will decrease (increase)
Volatility	If the share price volatility increases (decreases), Fair value will increase (decrease)

(4) Enforceable master netting agreement or similar agreement

Carrying amount of financial instruments recognized of which offset agreements are applicable as of December 31, 2017 and 2016 are as follows:

(In millions of won)	2017
	Gross financial instruments recognized		Amount offset			Net financial instruments presented on the statements of financial position		Relevant amount not offset on the statements of financial position			Net amount
								Financial instruments
Financial assets:
Derivatives(*)	￦	26,645		—			26,645		(19,875	)		6,770
Accounts receivable — trade and others		93,146		(92,409	)		737		—			737
	￦	119,791		(92,409	)		27,382		(19,875	)		7,507
Financial liabilities:
Derivatives(*)	￦	19,875		—			19,875		(19,875	)		—
Accounts payable — other and others		92,409		(92,409	)		—		—			—
	￦	112,284		(92,409	)		19,875		(19,875	)		—

(In millions of won)	2016
	Gross financial instruments recognized		Amount offset			Net financial instruments presented on the statements of financial position		Relevant amount not offset on the statements of financial position			Net amount
								Financial instruments
Financial assets:
Derivatives(*)	￦	87,566		—			87,566		(87,153	)		413
Accounts receivable — trade and others		114,135		(103,852	)		10,283		—			10,283
	￦	201,701		(103,852	)		97,849		(87,153	)		10,696
Financial liabilities:
Derivatives(*)	￦	87,153		—			87,153		(87,153	)		—
Accounts payable — other and others		103,852		(103,852	)		—		—			—
	￦	191,005		(103,852	)		87,153		(87,153	)		—

(*) The Group entered into derivative contracts which include enforceable master netting arrangement in accordance with International Swap and Derivatives Association (ISDA). Generally, all contracts made with the identical currencies are settled from one party to another by combining one net amount. In this case, all contracts are liquidated and paid off at net amount by evaluating liquidation value if credit events such as bankruptcy occur.

ISDAagreements do not allow the Group to exercise rights of set-off unless credit events such as bankruptcy occur. Therefore, assets and liabilities recognized in accordance with the agreements cannot be offset as the Group does not have enforceable rights of set-off.

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Related Parties and Others

12 Months Ended

Dec. 31, 2017

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Related Parties and Others

36. Related Parties and Others

(1) List of related parties

Relationship	Company
Ultimate Controlling Entity	SK Holdings Co., Ltd.
Joint ventures	Dogus Planet, Inc. and 3 others
Associates	SK hynix Inc. and 40 others
Others	The Ultimate Controlling Entity’s subsidiaries and associates, etc.

(2) Compensation for the key management

The Parent Company considers registered directors who have substantial role and responsibility in planning, operations, and relevant controls of the business as key management. The compensation given to such key management for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Salaries	￦	2,169		1,645		1,971
Defined benefits plan expenses		258		424		626
Share option		414		—		—
	￦	2,841		2,069		2,597

Compensation for the key management includes salaries, non-monetary salaries, and retirement benefits made in relation to the pension plan and compensation expenses related to share options granted.

(3) Transactions with related parties for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
		2017
Scope	Company	Operating revenue and others		Operating expense and others		Acquisition of property and equipment		Collection of loans
Ultimate Controlling Entity	SK Holdings Co., Ltd.(*1)	￦	25,049		600,600		283,556		—
Associates	F&U Credit information Co., Ltd.		3,431		52,150		153		—
	HappyNarae Co., Ltd.		3,025		29,276		68,472		—
	SK hynix Inc(*2)		123,873		251		—		—
	KEB HanaCard Co., Ltd.		17,873		15,045		—		—
	Others(*3)		10,720		33,389		940		204
			158,922		130,111		69,565		204
Others	SK Engineering & Construction Co., Ltd.		5,865		1,077		—		—
	SK Networks Co., Ltd.		21,694		1,220,251		671		—
	SK Networks Services Co., Ltd.		510		96,949		6,346		—
	SK Telesys Co., Ltd.		417		51,394		152,659		—
	SK TNS Co., Ltd.		137		37,051		494,621		—
	SK Energy Co., Ltd.		8,505		779		—		—
	SK Gas Co., Ltd.		2,727		4		—		—
	SK Innovation Co., Ltd.		7,639		950		—		—
	SK Shipping Co., Ltd.		3,183		35		—		—
	Ko-one energy service Co., Ltd		5,164		44		—		—
	SK infosec Co., Ltd.		1,185		52,634		15,648		—
	SKC INFRA SERVICE Co., Ltd.		19		46,900		47,163		—
	Others		18,233		28,209		17		—
			75,278		1,536,277		717,125		—
Total		￦	259,249		2,266,988		1,070,246		204

(*1) Operating expense and others include ￦203,635 million of dividends paid by the Parent Company.

(*2) Operating revenue and others include ￦87,660 million of dividends received from SK Hynix Inc. which was deducted from the investment in associates.

(*3) Operating revenue and others include ￦6,597 million of dividends received from the Korea IT Fund and others.

(In millions of won)		2016
Scope	Company	Operating revenue and others		Operating expense and others		Acquisition of property and equipment		Loans		Collection of loans
Ultimate Controlling Entity	SK Holdings Co., Ltd.(*1)	￦	23,104		652,855		235,502		—		—
Associates	F&U Credit information Co., Ltd.		2,865		47,905		—		—		—
	HappyNarae Co., Ltd.		304		15,506		38,984		—		—
	SK hynix Inc.(*2)		100,861		306		—		—		—
	KEB HanaCard Co., Ltd.		19,730		14,804		—		—		—
	Others(*3)		8,018		21,853		1,573		1,100		3,194
			131,778		100,374		40,557		1,100		3,194
Others	SK Engineering & Construction Co., Ltd.		5,916		1,739		10,694		—		—
	SK Networks Co., Ltd.		13,756		1,131,567		—		—		—
	SK Networks Services Co., Ltd.		1,248		94,906		6,793		—		—
	SK Telesys Co., Ltd.		419		52,488		142,605		—		—
	SK TNS Co., Ltd.		109		48,192		387,496		—		—
	SK Energy Co., Ltd.		7,670		834		—		—		—
	SK Gas Co., Ltd.		2,500		4		—		—		—
	SK Innovation Co., Ltd.		9,757		915		1,080		—		—
	SK Shipping Co., Ltd.		5,435		—		—		—		—
	Ko-one energy service Co., Ltd		6,005		46		—		—		—
	SK infosec Co., Ltd.		230		53,068		19,882		—		—
	SKC INFRA SERVICE Co., Ltd.		43		30,663		32,141		—		—
	Others		13,437		17,626		246		—		—
			66,525		1,432,048		600,937		—		—
Total		￦	221,407		2,185,277		876,996		1,100		3,194

(*1) Operating expense and others include ￦203,635 million of dividends paid by the Parent Company.

(*2) Operating revenue and others include ￦73,050 million of dividends paid by the associate which was deducted from the investment in associates.

(*3) Operating revenue and others include ￦6,082 million of dividends received from the Korea IT Fund.

(In millions of won)
		2015
Scope	Company	Operating revenue and others		Operating expense and others		Acquisition of property and equipment		Loans		Collection of loans
Ultimate Controlling Entity	SK Holdings Co., Ltd. (formerly, SK C&C Co., Ltd.)(*1)	￦	20,260		324,078		236,414		—		—
	SK Holdings Co., Ltd. (formerly, SK Holdings Co., Ltd.)(*2,3)		1,299		212,378		117		—		—
			21,559		536,456		236,531		—		—
Associates	F&U Credit information Co., Ltd.		2,510		43,967		—		—		—
	HappyNarae Co., Ltd.		297		6,886		13,495		—		—
	SK hynix Inc.(*4)		55,949		2,384		—		—		—
	SK Wyverns Baseball Club., Ltd.		3,849		18,544		—		—		204
	KEB HanaCard Co., Ltd.		21,414		16,057		—		—		—
	Xian Tianlong Science and Technology Co., Ltd.		—		—		—		8,287		—
	Others(*5)		6,397		11,917		1,864		690		—
			90,416		99,755		15,359		8,977		204
Other	SK Engineering & Construction Co., Ltd.		15,598		27,243		240,701		—		—
	SK Networks Co., Ltd.		11,923		1,257,975		2		—		—
	SK Networks Services Co., Ltd.		10,491		94,097		6,472		—		—
	SK Telesys Co., Ltd.		397		48,900		141,870		—		—
	SK Energy Co., Ltd.		9,930		978		—		—		—
	SK Gas Co., Ltd.		3,561		2		—		—		—
	Others		29,409		71,314		194,945		—		—
			81,309		1,500,509		583,990		—		—
Total		￦	193,284		2,136,720		835,880		8,977		204

(*1) On August 1, 2015, SK C&C Co., Ltd., the ultimate controlling entity of the Parent Company merged with SK Holdings Co., Ltd., its equity method investee, and changed its name to SK Holdings Co., Ltd.

(*2) These relates to transactions occurred before July 31, 2015, the date of merger with SK C&C Co., Ltd.

(*3) Operating expense and others include ￦191,416 million of dividends paid by the Parent Company.

(*4) Operating revenue and others include ￦43,830 million of dividends paid by SK hynix Inc. and was deducted from the investment in associates.

(*5) Operating revenue and others include ￦2,103 million and ￦457 million of dividends paid by Korea IT Fund and UniSK, respectively, and was deducted from the investments in associates.

(4) Account balances with related parties as of December 31, 2017 and 2016 are as follows:

(In millions of won)
		December 31, 2017
		Accounts receivable				Accounts payable
Scope	Company	Loans		Accounts receivable-trade and others		Accounts payable-other and others
Ultimate Controlling Entity	SK Holdings Co., Ltd.	￦	—		2,068		148,066
Associates	HappyNarae Co., Ltd.		—		15		6,865
	F&U Credit information Co., Ltd.		—		21		1,612
	SK hynix Inc.		—		2,803		94
	Wave City Development Co., Ltd.		—		38,412		—
	Daehan Kanggun BcN Co., Ltd.(*)		22,147		—		—
	KEB HanaCard Co., Ltd.		—		1,427		11,099
	S.M. Culture & Contents Co., Ltd.		—		448		8,963
	Xian Tianlong Science and Technology Co., Ltd.		7,032		—		—
	Others		611		2,272		1,164
			29,790		45,398		29,797
Other	SK Engineering & Construction Co., Ltd.		—		2,033		69
	SK Networks. Co., Ltd.		—		3,050		267,297
	SK Networks Services Co., Ltd.		—		15		9,522
	SK Telesys Co., Ltd.		—		36		58,346
	SK TNS Co., Ltd.		—		3		140,311
	SK Innovation Co., Ltd.		—		4,112		599
	SK Energy Co., Ltd.		—		2,965		582
	SK Gas Co., Ltd.		—		1,941		9
	Others		—		2,998		27,318
			—		17,153		504,053
Total		￦	29,790		64,619		681,916

(*) The Parent Company has recognized allowances for doubtful accounts on the entire balance of loans to Daehan Kanggun BcN Co., Ltd as of December 31, 2017.

(In millions of won)
		December 31, 2016
		Accounts receivable				Accounts payable
Scope	Company	Loans		Accounts receivable-trade and others		Accounts payable-other and others
Ultimate Controlling Entity	SK Holdings Co., Ltd.	￦	—		3,519		149,574
Associates	HappyNarae Co., Ltd.		—		18		21,063
	F&U Credit information Co., Ltd.		—		34		1,328
	SK hynix Inc.		—		22,379		92
	Wave City Development Co., Ltd.		—		38,412		—
	Daehan Kanggun BcN Co., Ltd.(*)		22,147		—		—
	KEB HanaCard Co., Ltd.		—		1,619		7,676
	Xian Tianlong Science and Technology Co., Ltd.		8,287		—		—
	Others		813		4,191		945
			31,247		66,653		31,104
Other	SK Engineering & Construction Co., Ltd.		—		1,808		4,975
	SK Networks. Co., Ltd.		—		3,254		247,728
	SK Networks Services Co., Ltd.		—		13		13,913
	SK Telesys Co., Ltd.		—		20		24,918
	SK TNS Co., Ltd.		—		3		68,276
	SK Innovation Co., Ltd.		—		1,350		892
	SK Energy Co., Ltd.		—		1,213		113
	SK Gas Co., Ltd.		—		1,769		9
	Others		—		2,783		30,209
			—		12,213		391,033
Total		￦	31,247		82,385		571,711

(*) The Parent Company has recognized allowances for doubtful accounts on the entire balance of loans to Daehan Kanggun BcN Co., Ltd. as of December 31, 2016.

(5) SK m&service Co., Ltd., a subsidiary of the Parent Company, has entered into a performance agreement with SK Energy Co., Ltd. and provided a blank note to SK Energy Co., Ltd., with regard to this transaction.

(6) As of December 31, 2017, the Group provides with USD 12,240,000 of payment guarantees for the borrowings of the Celcom Planet, the joint ventures of the Group.

(7) There were additional investments in associates and joint ventures during the years ended December 31, 2017 and 2016 as presented in Note 12.

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Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

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Commitments and Contingencies

37. Commitments and Contingencies

(1) Collateral assets and commitments

SK Broadband Co., Ltd., a subsidiary of the Parent Company, has pledged its properties as collateral for leases on buildings in the amount of ￦4,144 million as of December 31, 2017.

SK Broadband Co., Ltd., has guaranteed for employees’ borrowings relating to employee stock ownership program and provided short-term financial instruments amounting to ￦300 million as collateral as of December 31, 2017.

(2) Legal claims and litigations

As of December 31, 2017 the Group is involved in various legal claims and litigation. Provision recognized in relation to these claims and litigation is immaterial. In connection with those legal claims and litigation for which no provision was recognized, management does not believe the Group has a present obligation, nor is it expected any of these claims or litigation will have a significant impact on the Group’s financial position or operating results in the event an outflow of resources is ultimately necessary.

(3) Accounts receivables from sale of handsets

The sales agents of the Parent Company sell handsets to the Parent Company’s subscribers on an installment basis. During the year ended December 31, 2017, the Parent Company entered into a comprehensive agreement to purchase the accounts receivables from handset sales with agents and to transfer the accounts receivables from handset sales to special purpose companies which were established with the purpose of liquidating receivables, respectively.

The accounts receivables from sale of handsets amounting to ￦1,111,614 million as of December 31, 2017, which the Parent Company purchased according to the relevant comprehensive agreement are recognized as accounts receivable — other and long-term accounts receivable — other.

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Statements of Cash Flows

12 Months Ended

Dec. 31, 2017

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Statements of Cash Flows

38. Statements of Cash Flows

(1) Adjustments for income and expenses from operating activities for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017			2016			2015
Interest income	￦	(76,045	)		(54,353	)		(45,884	)
Dividend		(12,416	)		(19,161	)		(16,102	)
Gain on foreign currency translation		(7,110	)		(5,085	)		(5,090	)
Gain on disposal of long-term investment securities		(4,890	)		(459,349	)		(10,786	)
Gain on valuation of derivatives		(223,943	)		(4,132	)		(1,927	)
Gain relating to investments in associates and joint ventures, net		(2,245,732	)		(544,501	)		(786,140	)
Gain on sale of accounts receivable — trade		(18,548	)		(18,638	)		—
Gain on disposal of property and equipment and intangible assets		(13,991	)		(6,908	)		(7,140	)
Gain relating to financial assets at fair value through profit or loss		(33	)		(25	)		—
Gain related to financial liabilities at fair value through profit or loss		—			(121	)		(5,188	)
Reversal of impairment loss on available-for-sale financial assets		(9,900	)		—			—
Other income		(1,129	)		(2,123	)		(7,577	)
Interest expenses		299,100			290,454			297,662
Loss on foreign currency translation		8,419			3,991			4,750
Loss on disposal of long-term investment securities		36,024			2,919			2,599
Other finance costs		14,519			5,255			21,787
Loss on sale of accounts receivable — trade		9,682			—			—
Loss on settlement of derivatives		10,031			3,428			4,845
Income tax expense		745,654			436,038			519,480
Expense related to defined benefit plan		127,696			118,143			110,021
Share option		414			—			—
Depreciation and amortization		3,247,519			3,068,558			2,993,486
Bad debt expense		34,584			37,820			60,450
Loss on disposal of property and equipment and intangible assets		60,086			63,797			21,392
Impairment loss on property and equipment and intangible assets		54,946			24,506			35,845
Loss relating to financial liabilities at fair value through profit or loss		678			4,018			526
Bad debt for accounts receivable — other		5,793			40,312			15,323
Loss on impairment of investment assets		9,003			24,033			42,966
Other expenses		46,353			30,685			4,845
	￦	2,096,764			3,039,561			3,250,143

(2) Changes in assets and liabilities from operating activities for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017			2016			2015
Accounts receivable — trade	￦	46,144			88,549			7,554
Accounts receivable — other		(159,960	)		(446,286	)		(11,108	)
Accrued income		14			445			116
Advance payments		(1,269	)		47,615			(35,906	)
Prepaid expenses		(28,362	)		(30,311	)		(40,464	)
Value-Added Tax refundable		(3,080	)		(4,587	)		1,385
Inventories		(17,958	)		798			(7,814	)
Long-term accounts receivable — other		(137,979	)		(147,117	)		—
Guarantee deposits		14,696			4,844			(11,238	)
Accounts payable — trade		(26,151	)		75,585			12,442
Accounts payable — other		134,542			316,464			(107,114	)
Advanced receipts		(13,470	)		37,429			6,421
Withholdings		(13,041	)		107,516			(191,209	)
Deposits received		(4,916	)		(2,153	)		(9,661	)
Accrued expenses		116,065			173,072			(28,845	)
Value-Added Tax payable		7,505			(4,072	)		3,494
Unearned revenue		(339	)		(36,209	)		(115,187	)
Provisions		(20,488	)		20,235			(30,562	)
Long-term provisions		(2,449	)		4,115			(4,447	)
Plan assets		(95,828	)		(125,440	)		(67,831	)
Retirement benefit payment		(60,883	)		(55,350	)		(58,513	)
Others		5,739			(11,378	)		2,753
		￦(261,468)			13,764			(685,734	)

(3) Significant non-cash transactions for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Increase of accounts payable — other related to acquisition of property and equipment and intangible assets	￦	44,214		1,511,913		39,973

(4) Reconciliation of liabilities arising from financing activities for the year ended December 31, 2017 is as follows:

(In millions of won)
	January 1, 2017			Cash flows			Non-cash transactions								December 31, 2017
							Exchange rate changes			Fair value changes			Other changes
Total liabilities from financing activities
Short-term borrowings	￦	2,614			127,386			—			—			—		130,000
Long-term borrowings		172,906			87,299			(7,898	)		—			510		252,817
Debentures		7,194,207			130,558			(245,456	)		—			6,878		7,086,187
Long-term payables — other		1,918,024			(305,476	)		—			—			28,533		1,641,081
Derivative financial liabilities		87,153			(105,269	)		13,281			39,267			5,038		39,470
Derivative financial assets		(214,770	)		188			922			(40,235	)		682		(253,213	)
	￦	9,160,134			(65,314	)		(239,151	)		(968	)		41,641		8,896,342
Other cash flows from financing activities
Payments of cash dividends	￦				(706,091	)
Payments of interest on hybrid bond					(16,840	)
Transactions with non-controlling interests					(38,373	)
					(761,304	)
Total	￦				(826,618	)

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Cash Dividends paid to the Parent Company

12 Months Ended

Dec. 31, 2017

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Cash Dividends paid to the Parent Company

39. Cash Dividends paid to the Parent Company

Cash dividends received from the consolidated subsidiaries and associates for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Cash dividends received from consolidated subsidiaries	￦	—		15,693		—
Cash dividends received from associates		89,063		79,132		46,390
	￦	89,063		94,825		46,390

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Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

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Operating segments

(1)    Operating segments

An operating segment is a component of the Group that engages in business activities from which it may earn revenues and incur expenses, including revenues and expenses that relate to transactions with any of the Group’s other components. The Group’s operating segments have been determined to be each business unit, for which the Group generates separately identifiable financial information that is regularly reported to the chief operating decision maker for the purpose of resource allocation and assessment of segment performance. The Group has four reportable segments which consist of cellular services, fixed-line telecommunication services, e-commerce services and others, as described in Note 5. Segment results that are reported to the chief operating decision maker include items directly attributable to a segment as well as those that can be allocated on a reasonable basis.

The Group’s chief operating decision maker receives and reviews operating income based on Korean IFRS as the measure of segment profit and loss for each operating segment. Segment operating income differs from consolidated operating income used in the Group’s consolidated statements of income. Segment operating profit does not include certain items such as fee revenues, gain/loss from disposal of property, plant, equipment and intangible assets, impairment losses on property, plant, equipment and intangible assets, donations, bad debt expense and penalties. The chief operating decision maker does not receive any information about segment assets and liabilities.

Basis of consolidation

(2)    Basis of consolidation

(i)    Business combination

A business combination is accounted for by applying the acquisition method, unless it is a combination involving entities or businesses under common control.

Consideration transferred is generally measured at fair value, identical to the measurement of identifiable net assets acquired at fair value. The difference between the acquired company’s fair value and the consideration transferred is accounted for goodwill. Any goodwill that arises is tested annually for impairment. Any gain on a bargain purchase is recognized in profit or loss immediately. Acquisition-related costs are expensed in the periods in which the costs are incurred and the services are received excluding costs to issue debt or equity securities recognized based on IAS 32 and 39.

Consideration transferred does not include the amount settled in relation to the pre-existing relationship and the amount settled in relation to the pre-existing relationship is generally recognized through profit or loss.

Contingent consideration is measured at fair value at the acquisition date. Contingent consideration classified as equity is not remeasured and its subsequent settlement is accounted for within equity. If contingent consideration is not classified as equity, the Group subsequently recognizes changes in fair value of contingent consideration through profit or loss.

(ii)    Non-controlling interests

Non-controlling interests are measured at their proportionate share of the acquiree’s identifiable net assets at the date of acquisition.

Changes in a Controlling Company’s ownership interest in a subsidiary that do not result in the Controlling Company losing control of the subsidiary are accounted for as equity transactions.

(iii)    Subsidiaries

Subsidiaries are entities controlled by the Group. The Group controls an investee when it is exposed, or has rights, to variable returns from its involvement with the investee and has the ability to affect those returns through its power over the investee. Consolidation of an investee begins from the date the Group obtains control of the investee and cease when the Group loses control of the investee.

(iv)    Loss of control

If the Group loses control of a subsidiary, the Group derecognizes the assets and liabilities of the former subsidiary from the consolidated statement of financial position and recognizes gain or loss associated with the loss of control attributable to the former controlling interest. Any investment retained in the former subsidiary is recognized at its fair value when control is lost.

(v)    Interest in investees accounted for using the equity method

Interest in investees accounted for using the equity method composed of interest in associates and joint ventures. An associate is an entity in which the Group has significant influence, but not control, over the entity’s financial and operating policies. A joint venture is a joint arrangement whereby the Group that has joint control of the arrangement has rights to the net assets of the arrangement.

The investment in an associate and a joint venture is initially recognized at cost including transaction costs and the carrying amount is increased or decreased to recognize the Group’s share of the profit or loss and changes in equity of the associate or the joint venture after the date of acquisition.

(vi)    Intra-group transactions

Intra-group balances and transactions, and any unrealized income and expenses arising from intra-group transactions, are eliminated in preparing the consolidated financial statements. The Group’s share of unrealized gain incurred from transactions with investees accounted for using the equity method are eliminated and unrealized loss are eliminated using the same basis if there are no evidence of asset impairments.

(vii)    Business combinations under common control

SK Holdings Co., Ltd. is the ultimate controlling entity of the Group. The assets and liabilities acquired under business combination under common control are recognized at the carrying amounts in the ultimate controlling shareholder’s consolidated financial statements. The difference between consideration and carrying amount of net assets acquired is added to or subtracted from capital surplus and others.

Cash and cash equivalents

(3)    Cash and cash equivalents

Cash and cash equivalents comprise cash balances, call deposits and financial assets with maturities of three months or less from the acquisition date that are easily convertible to cash and subject to an insignificant risk of changes in their fair value.

Inventories

(4)    Inventories

Inventories are stated at the acquisition cost using the average method. During the period, a perpetual inventory system is used to track inventory quantities, which is adjusted to the physical inventory counts performed at the period end. When the net realizable value of inventories is less than the acquisition cost, the carrying amount is reduced to the net realizable value and any difference is charged to current operations as operating expenses.

Non-derivative financial assets

(5)    Non-derivative financial assets

The Group recognizes and measures non-derivative financial assets by the following four categories: financial assets at fair value through profit or loss, held-to-maturity investments, loans and receivables and available-for-sale financial assets. The Group recognizes financial assets in the consolidated statement of financial position when the Group becomes a party to the contractual provisions of the instrument.

Upon initial recognition, non-derivative financial assets not at fair value through profit or loss are measured at their fair value plus transaction costs that are directly attributable to the acquisition of the asset.

(i)    Financial assets at fair value through profit or loss

A financial asset is classified as financial asset at fair value through profit or loss if it is held for trading or is designated as such upon initial recognition. Upon initial recognition, transaction costs are recognized in profit or loss when incurred. Financial assets at fair value through profit or loss are measured at fair value, and changes therein are recognized in profit or loss.

(ii)    Held-to-maturity investments

A non-derivative financial asset with a fixed or determinable payment and fixed maturity, for which the Group has the positive intention and ability to hold to maturity, are classified as held-to-maturity investment. Subsequent to initial recognition, held-to-maturity investments are measured at amortized cost using the effective interest rate method.

(iii)    Loans and receivables

Loans and receivables are financial assets with fixed or determinable payments that are not quoted in an active market. Subsequent to initial recognition, loans and receivables are measured at amortized cost using the effective interest method except for loans and receivables of which the effect of discounting is immaterial.

(iv)    Available-for-sale financial assets

Available-for-sale financial assets are those non-derivative financial assets that are designated as available-for-sale or are not classified as financial assets at fair value through profit or loss, held-to-maturity investments or loans and receivables. Subsequent to initial recognition, they are measured at fair value with changes in fair value, net of any tax effect, recorded in other comprehensive income (OCI) in equity. Investments in equity instruments that do not have a quoted market price in an active market and whose fair value cannot be reliably measured are measured at cost.

(v)    De-recognition of financial assets

The Group derecognizes a financial asset when the contractual rights to the cash flows from the asset expire, or it transfers the rights to receive the contractual cash flows on the financial asset in a transaction in which substantially all the risks and rewards of ownership of the financial asset are transferred. Any interest in transferred financial assets that is created or retained by the Group is recognized as a separate asset or liability. If the Group retains substantially all the risks and rewards of ownership of the transferred financial assets, the Group continues to recognize the transferred financial assets and recognizes financial liabilities for the consideration received.

(vi)    Offsetting between financial assets and financial liabilities

Financial assets and liabilities are offset and the net amount is presented in the consolidated statement of financial position only when the Group currently has a legally enforceable right to offset the recognized amounts, and there is the intention to settle on a net basis or to realize the asset and settle the liability simultaneously.

Derivative financial instruments, including hedge accounting

(6)    Derivative financial instruments, including hedge accounting

Derivatives are initially recognized at fair value. Subsequent to initial recognition, derivatives are measured at fair value, and changes therein are accounted for as described below.

(i)    Hedge accounting

The Group holds forward exchange contracts, interest rate swaps, currency swaps and other derivative contracts to manage interest rate risk and foreign exchange risk. The Group designates derivatives as hedging instruments to hedge the risk of changes in the fair value of assets, liabilities or firm commitments (a fair value hedge) and foreign currency risk of highly probable forecasted transactions or firm commitments (a cash flow hedge).

On initial designation of the hedge, the Group formally documents the relationship between the hedging instrument(s) and hedged item(s), including the risk management objectives and strategy in undertaking the hedge transaction, together with the methods that will be used to assess the effectiveness of the hedging relationship.

Fair value hedge

Changes in the fair value of a derivative hedging instrument designated as a fair value hedge are recognized in profit or loss. The gain or loss from remeasuring the hedging instrument at fair value for a derivative hedging instrument and the gain or loss on the hedged item attributable to the hedged risk are recognized in profit or loss in the same line item of the consolidated statement of income.

The Group discontinues fair value hedge accounting if the hedging instrument expires or is sold, terminated or exercised, or if the hedge no longer meets the criteria for hedge accounting. Any adjustment arising from gain or loss on the hedged item attributable to the hedged risk is amortized to profit or loss from the date the hedge accounting is discontinued.

Cash flow hedge

When a derivative is designated to hedge the variability in cash flows attributable to a particular risk associated with a recognized asset or liability or a highly probable forecasted transaction that could affect profit or loss, the effective portion of changes in the fair value of the derivative is recognized in other comprehensive income, net of tax, and presented in the hedging reserve in equity. Any ineffective portion of changes in the fair value of the derivative is recognized immediately in profit or loss. If the hedging instrument no longer meets the criteria for hedge accounting, expires or is sold, terminated, exercised, or the designation is revoked, then hedge accounting is discontinued prospectively. The cumulative gain or loss on the hedging instrument that has been recognized in other comprehensive income is reclassified to profit or loss in the periods during which the forecasted transaction occurs. If the forecasted transaction is no longer expected to occur, then the balance in other comprehensive income is recognized immediately in profit or loss.

(ii)    Separable embedded derivatives

Embedded derivatives are separated from the host contract and accounted for separately only if the following criteria have been met:

(a) the economic characteristics and risks of the embedded derivative are not closely related to those of the host contract;

(b) a separate instrument with the same terms as the embedded derivative would meet the definition of a derivative; and

(c) the hybrid (combined) instrument is not measured at fair value with changes in fair value recognized in profit or loss.

Changes in the fair value of separable embedded derivatives are recognized immediately in profit or loss.

(iii)    Other derivative financial instruments

Changes in the fair value of other derivative financial instrument not designated as a hedging instrument are recognized immediately in profit or loss.

Impairment of financial assets

(7)    Impairment of financial assets

A financial asset not carried at fair value through profit or loss is assessed at each reporting date to determine whether there is objective evidence that it is impaired. A financial asset is impaired if objective evidence indicates that a loss event has occurred after the initial recognition of the asset, and that the loss event had a negative effect on the estimated future cash flows of that asset that can be estimated reliably. However, losses expected as a result of future events, regardless of likelihood, are not recognized.

Objective evidence that a financial asset is impaired includes following loss events:

• significant financial difficulty of the issuer or obligor;

• a breach of contract, such as default or delinquency in interest or principal payments;

• the lender, for economic or legal reasons relating to the borrower’s financial difficulty, granting to the borrower a concession that the lender would not otherwise consider;

• it becoming probable that the borrower will enter bankruptcy or other financial reorganization;

• the disappearance of an active market for that financial asset because of financial difficulties; or

• observable data indicating that there is a measurable decrease in the estimated future cash flows from a group of financial assets since the initial recognition of those assets, although the decrease cannot yet be identified with the individual financial assets in the group.

In addition, for an investment in an equity security, a significant or prolonged decline in its fair value below its cost is objective evidence of impairment.

If financial assets have objective evidence that they are impaired, impairment losses are measured and recognized.

(i)    Financial assets measured at amortized cost

An impairment loss in respect of a financial asset measured at amortized cost is calculated as the difference between its carrying amount and the present value of its estimated future cash flows discounted at the asset’s original effective interest rate. The Group can recognize impairment losses directly or by establishing an allowance account. If, in a subsequent period, the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized (such as an improvement in the debtor’s credit rating), the previously recognized impairment loss is reversed either directly or by adjusting an allowance account.

(ii)    Financial assets carried at cost

If there is objective evidence that an impairment loss has occurred on an unquoted equity instrument that is not carried at fair value because its fair value cannot be reliably measured, or on a derivative asset that is linked to and must be settled by delivery of such an unquoted equity instrument, the amount of the impairment loss is measured as the difference between the carrying amount of the financial asset and the present value of estimated future cash flows discounted at the current market rate of return for a similar financial asset. Such impairment losses are not reversed.

(iii)    Available-for-sale financial assets

When a decline in the fair value of an available-for-sale financial asset has been recognized in other comprehensive income and there is objective evidence that the asset is impaired, the cumulative loss that had been recognized in other comprehensive income is reclassified from equity to profit or loss as a reclassification adjustment even though the financial asset has not been derecognized. Impairment losses recognized in profit or loss for an investment in an equity instrument classified as available-for-sale is not reversed through profit or loss subsequently. If, in a subsequent period, the fair value of a debt instrument classified as available-for-sale increases and the increase can be objectively related to an event occurring after the impairment loss was recognized in profit or loss, the impairment loss is reversed, with the amount of the reversal recognized in profit or loss.

Property and equipment

(8)    Property and equipment

Property and equipment are initially measured at cost. The cost of property and equipment includes expenditures arising directly from the construction or acquisition of the asset, any costs directly attributable to bringing the asset to the location and condition necessary for it to be capable of operating in the manner intended by management and the initial estimate of the costs of dismantling and removing the item and restoring the site on which it is located.

Subsequent to initial recognition, an item of property and equipment is carried at its cost less any accumulated depreciation and any accumulated impairment losses.

Subsequent costs are recognized in the carrying amount of property and equipment at cost or, if appropriate, as a separate item if it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day servicing are recognized in profit or loss as incurred.

Property and equipment, except for land, are depreciated on a straight-line basis over estimated useful lives that appropriately reflect the pattern in which the asset’s future economic benefits are expected to be consumed. A component that is significant compared to the total cost of property and equipment is depreciated over its separate useful life.

Gains and losses on disposal of an item of property and equipment are determined by comparing the proceeds from disposal with the carrying amount of property and equipment and are recognized as other non-operating income (loss).

The estimated useful lives of the Group’s property and equipment are as follows:

	Useful lives (years)
Buildings and structures		15 ~ 40
Machinery		3 ~ 15
Other property and equipment		2 ~ 10

Depreciation methods, useful lives and residual values are reviewed at the end of each reporting date and adjusted, if appropriate. The change is accounted for as a change in an accounting estimate.

Borrowing costs

(9)    Borrowing costs

The Group capitalizes borrowing costs directly attributable to the acquisition, construction or production of a qualifying asset as part of the cost of that asset. Other borrowing costs are recognized in expense as incurred. A qualifying asset is an asset that requires a substantial period of time to get ready for its intended use or sale. Financial assets are not qualifying assets. Assets that are ready for their intended use or sale when acquired are not qualifying assets.

To the extent that the Group borrows funds specifically for the purpose of obtaining a qualifying asset, the Group determines the amount of borrowing costs eligible for capitalization as the actual borrowing costs incurred on that borrowing during the period less any investment income on the temporary investment of those borrowings. To the extent that the Group borrows funds generally and uses them for the purpose of obtaining a qualifying asset, the Group determines the amount of borrowing costs eligible for capitalization by applying a capitalization rate to the expenditures on that asset. The capitalization rate is the weighted average of the borrowing costs applicable to the borrowings of the Group that are outstanding during the period, other than borrowings made specifically for the purpose of obtaining a qualifying asset. The amount of borrowing costs that the Group capitalizes during a period do not exceed the amount of borrowing costs incurred during that period.

Intangible assets

(10)    Intangible assets

Intangible assets are measured initially at cost and, subsequently, are carried at cost less accumulated amortization and accumulated impairment losses.

Amortization of intangible assets except for goodwill is calculated on a straight-line basis over the estimated useful lives of intangible assets from the date that they are available for use. The residual value of intangible assets is zero. However, club memberships are expected to be available for use as there are no foreseeable limits to the periods. This intangible asset is determined as having indefinite useful lives and not amortized.

The estimated useful lives of the Group’s intangible assets are as follows:

	Useful lives (years)
Frequency usage rights	5 ~ 13
Land usage rights	5
Industrial rights	5, 10
Development costs	3 ~ 5
Facility usage rights	10, 20
Customer relations	3 ~ 7
Other	3 ~ 20

Amortization periods and the amortization methods for intangible assets with finite useful lives are reviewed at the end of each reporting period. The useful lives of intangible assets that are not being amortized are reviewed at the end of each reporting period to determine whether events and circumstances continue to support indefinite useful life assessments for those assets. Changes are accounted for as changes in accounting estimates.

Expenditures on research activities are recognized in profit or loss as incurred. Development expenditures are capitalized only if development costs can be measured reliably, the product or process is technically and commercially feasible, future economic benefits are probable, and the Group intends to and has sufficient resources to complete development and to use or sell the asset. Other development expenditures are recognized in profit or loss as incurred.

Subsequent expenditures are capitalized only when they increase the future economic benefits embodied in the specific asset to which it relates. All other expenditures, including expenditures on internally generated goodwill and brands, are recognized in profit or loss as incurred.

Government grants

(11)    Government grants

Government grants are not recognized unless there is reasonable assurance that the Group will comply with the grant’s conditions and that the grant will be received.

(i)    Grants related to assets

Government grants whose primary condition is that the Group purchases, constructs or otherwise acquires a long-term asset are deducted in calculating the carrying amount of the asset. The grant is recognized in profit or loss over the life of a depreciable asset as a reduction to depreciation expense.

(ii)    Grants related to income

Government grants which are intended to compensate the Group for expenses incurred are deducted from the related expenses.

Investment property

(12)    Investment property

Property held for the purpose of earning rentals or benefiting from capital appreciation is classified as investment property. Investment property is initially measured at its cost. Transaction costs are included in the initial measurement. Subsequently, investment property is carried at depreciated cost less any accumulated impairment losses.

Subsequent costs are recognized in the carrying amount of investment property at cost or, if appropriate, as a separate item if it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day servicing are recognized in profit or loss as incurred.

Investment property except for land, are depreciated on a straight-line basis over 15~40 years as estimated useful lives.

Depreciation methods, useful lives and residual values are reviewed at the end of each reporting date and adjusted, if appropriate. The change is accounted for as a change in an accounting estimate.

Impairment of non-financial assets

(13)    Impairment of non-financial assets

The carrying amounts of the Group’s non-financial assets, other than assets arising from employee benefits, inventories, deferred tax assets and non-current assets held for sale, are reviewed at the end of the reporting period to determine whether there is any indication of impairment. If any such indication exists, then the asset’s recoverable amount is estimated. Goodwill and intangible assets that have indefinite useful lives or that are not yet available for use, irrespective of whether there is any indication of impairment, are tested for impairment annually by comparing their recoverable amount to their carrying amount.

The Group estimates the recoverable amount of an individual asset, if it is impossible to measure the individual recoverable amount of an asset, then the Group estimates the recoverable amount of cash-generating unit (“CGU”). A CGU is the smallest identifiable group of assets that generates cash inflows that are largely independent of the cash inflows from other assets or groups of assets. The recoverable amount of an asset or CGU is the greater of its value in use and its fair value less costs to sell. The value in use is estimated by applying a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset or CGU for which estimated future cash flows have not been adjusted, to the estimated future cash flows expected to be generated by the asset or CGU.

An impairment loss is recognized in profit or loss to the extent the carrying amount of the asset exceeds its recoverable amount.

Goodwill acquired in a business combination is allocated to each CGU that is expected to benefit from the synergies arising from the business acquired. Any impairment identified at the CGU level will first reduce the carrying value of goodwill and then be used to reduce the carrying amount of the other assets in the CGU on a pro rata basis. Except for impairment losses in respect of goodwill which are never reversed, an impairment loss is reversed if there has been a change in the estimates used to determine the recoverable amount. An impairment loss is reversed only to the extent that the asset’s carrying amount does not exceed the carrying amount that would have been determined, net of depreciation or amortization, if no impairment loss had been recognized.

Leases

(14)    Leases

The Group classifies and accounts for leases as either a finance or operating lease, depending on the terms. Leases where the Group assumes substantially all of the risks and rewards of ownership are classified as finance leases. All other leases are classified as operating leases.

(i)    Finance leases

At the commencement of the lease term, the Group recognizes as finance assets and finance liabilities in its consolidated statement of financial position, the lower amount of the fair value of the leased property and the present value of the minimum lease payments, each determined at the inception of the lease. Any initial direct costs are added to the amount recognized as an asset.

Minimum lease payments are apportioned between the finance charge and the reduction of the outstanding liability. The finance charge is allocated to each period during the lease term so as to produce a constant periodic rate of interest on the remaining balance of the liability. Contingent rents are charged as expenses in the periods in which they are incurred.

The depreciable amount of a leased asset is allocated to each accounting period during the period of expected use on a systematic basis consistent with the depreciation policy the Group adopts for depreciable assets that are owned. If there is no reasonable certainty that the Group will obtain ownership by the end of the lease term, the asset is fully depreciated over the shorter of the lease term and its useful life. The Group reviews to determine whether the leased assets are impaired at the reporting date.

(ii)    Operating leases

Leases where the lessor retains a significant portion of the risks and rewards of ownership are classified as operating leases. Payments made under operating leases (net of any incentives received from the lessor) are recognized in profit or loss on a straight-line basis over the period of the lease.

(iii)    Determining whether an arrangement contains a lease

Determining whether an arrangement is, or contains, a lease is based on the substance of the arrangement and requires an assessment of whether fulfillment of the arrangement is dependent on the use of a specific asset and the arrangement conveys a right to use the asset.

At inception or reassessment of the arrangement, the Group separates payments and other consideration required by such an arrangement into those for the lease and those for other elements on the basis of their relative fair values. If the Group concludes for a financial lease that it is impracticable to separate the payments reliably, the Group recognizes an asset and a liability at an amount equal to the fair value of the underlying asset that was identified as the subject of the lease. Subsequently, the liability is reduced as payments are made and an imputed finance charge on the liability is recognized using the Group’s incremental borrowing rate of interest.

Non-current assets held for sale

(15)    Non-current assets held for sale

Non-current assets, or disposal groups comprising assets and liabilities, that are expected to be recovered primarily through sale rather than through continuing use, are classified as held for sale. In order to be classified as held for sale, the asset (or disposal group) must be available for immediate sale in its present condition and its sale must be highly probable. The assets or disposal group that are classified as non-current assets held for sale are measured at the lower of their carrying amount and fair value less cost to sell. The Group recognizes an impairment loss for any initial or subsequent write-down of an asset (or disposal group) to fair value less costs to sell, and a gain for any subsequent increase in fair value less costs to sell, up to the cumulative impairment loss previously recognized in accordance with IAS 36, Impairment of Assets.

A non-current asset that is classified as held for sale or part of a disposal group classified as held for sale is not depreciated (or amortized).

Non-derivative financial liabilities

(16)    Non-derivative financial liabilities

The Group classifies non-derivative financial liabilities into financial liabilities at fair value through profit or loss or other financial liabilities in accordance with the substance of the contractual arrangement. The Group recognizes financial liabilities in the consolidated statement of financial position when the Group becomes a party to the contractual provisions of the financial liability.

(i)    Financial liabilities at fair value through profit or loss

Financial liabilities at fair value through profit or loss include financial liabilities held for trading or designated as such upon initial recognition. Subsequent to initial recognition, financial liabilities at fair value through profit or loss are measured at fair value, and changes therein are recognized in profit or loss. Upon initial recognition, transaction costs that are directly attributable to the issue of the financial liability are recognized in profit or loss as incurred.

(ii)    Other financial liabilities

Non-derivative financial liabilities other than financial liabilities at fair value through profit or loss are classified as other financial liabilities. At the date of initial recognition, other financial liabilities are measured at fair value minus transaction costs that are directly attributable to the issue of the financial liability. Subsequent to initial recognition, other financial liabilities are measured at amortized cost using the effective interest method.

The Group derecognizes a financial liability from the consolidated statement of financial position when it is extinguished (i.e. when the obligation specified in the contract is discharged, cancelled or expires).

Employee benefits

(17)    Employee benefits

(i)    Short-term employee benefits

Short-term employee benefits are employee benefits that are due to be settled within 12 months after the end of the period in which the employees render the related service. When an employee has rendered service to the Group during an accounting period, the Group recognizes the undiscounted amount of short-term employee benefits expected to be paid in exchange for that service.

(ii)    Other long-term employee benefits

Other long-term employee benefits include employee benefits that are settled beyond 12 months after the end of the period in which the employees render the related service. The Group’s net obligation in respect of long-term employee benefits is the amount of future benefit that employees have earned in return for their service in the current and prior periods. That benefit is discounted to determine its present value. Remeasurements are recognized in profit or loss in the period in which they arise.

(iii)    Retirement benefits: defined contribution plans

When an employee has rendered service to the Group during a period, the Group recognizes the contribution payable to a defined contribution plan in exchange for that service as a liability (accrued expense), after deducting any contribution already paid. If the contribution already paid exceeds the contribution due for service before the end of the reporting period, the Group recognizes that excess as an asset (prepaid expense) to the extent that the prepayment will lead to a reduction in future payments or a cash refund.

(iv)    Retirement benefits: defined benefit plans

At the end of reporting period, defined benefits liabilities relating to defined benefit plans are recognized at present value of defined benefit obligations net of fair value of plan assets.

The calculation is performed annually by an independent actuary using the projected unit credit method. When the fair value of plan assets exceeds the present value of the defined benefit obligation, the Group recognizes an asset, to the extent of the present value of any economic benefits available in the form of refunds from the plan or reduction in the future contributions to the plan.

Remeasurements of the net defined benefit liability, which comprise actuarial gains and losses, the return on plan assets (excluding interest) and the effect of the asset ceiling (if any, excluding interest), are recognized immediately in other comprehensive income. The Group determines net interests on net defined benefit liability (asset) by multiplying discount rate determined at the beginning of the annual reporting period and considers changes in net defined benefit liability (asset) from contributions and benefit payments. Net interest costs and other costs relating to the defined benefit plan are recognized through profit or loss.

When the plan amendment or curtailment occurs, gains or losses on amendment or curtailment in benefits for the past service provided are recognized through profit or loss. The Group recognizes gain or loss on a settlement when the settlement of defined benefit plan occurs.

(v)    Termination benefits

The Group recognizes a liability and expense for termination benefits at the earlier of the period when the Group can no longer withdraw the offer of those benefits and the period when the Group recognizes costs for a restructuring that involves the payment of termination benefits. If benefits are payable more than 12 months after the reporting period, they are discounted to their present value.

Provisions

(18)    Provisions

Provisions are recognized when the Group has a present legal or constructive obligation as a result of a past event, it is probable that an outflow of resources embodying economic benefits will be required to settle the obligation and a reliable estimate can be made of the amount of the obligation.

The risks and uncertainties that inevitably surround many events and circumstances are taken into account in reaching the best estimate of a provision. Where the effect of the time value of money is material, provisions are determined at the present value of the expected future cash flows.

Where some or all of the expenditures required to settle a provision are expected to be reimbursed by another party, the reimbursement is recognized when, and only when, it is virtually certain that reimbursement will be received if the entity settles the obligation. The reimbursement is treated as a separate asset.

Provisions are reviewed at the end of each reporting period and adjusted to reflect the current best estimates. If it is no longer probable that an outflow of resources embodying economic benefits will be required to settle the obligation, the provision is reversed.

A provision is used only for expenditures for which the provision was originally recognized.

Transactions in foreign currencies

(19)    Transactions in foreign currencies

(i)    Foreign currency transactions

Transactions in foreign currencies are translated to the functional currency of Group at exchange rates at the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are retranslated to the functional currency using the reporting date’s exchange rate. Non-monetary assets and liabilities denominated in foreign currencies that are measured at fair value are retranslated to the functional currency at the exchange rate at the date that the fair value was determined.

Foreign currency differences arising on retranslation are recognized in profit or loss, except for differences arising on the retranslation of available-for-sale equity instruments.

(ii)    Foreign operations

If the presentation currency of the Group is different from a foreign operation’s functional currency, the financial statements of the foreign operation are translated into the presentation currency using the following methods:

The assets and liabilities of foreign operations, whose functional currency is not the currency of a hyperinflationary economy, are translated to presentation currency at exchange rates at the reporting date. The income and expenses of foreign operations are translated to functional currency at exchange rates at the dates of the transactions. Foreign currency differences are recognized in other comprehensive income.

Any goodwill arising on the acquisition of a foreign operation and any fair value adjustments to the carrying amounts of assets and liabilities arising on the acquisition of that foreign operation is treated as assets and liabilities of the foreign operation. Thus they are expressed in the functional currency of the foreign operation and translated at the closing rate at the reporting date.

When a foreign operation is disposed of, the relevant amount in the translation is transferred to profit or loss as part of the profit or loss on disposal. On the partial disposal of a subsidiary that includes a foreign operation, the relevant proportion of such cumulative amount is reattributed to non-controlling interest. In any other partial disposal of a foreign operation, the relevant proportion is reclassified to profit or loss.

Share capital

(20)    Share capital

Ordinary shares are classified as equity. Incremental costs directly attributable to the issuance of ordinary shares and share options are recognized as a deduction from equity, net of any tax effects.

When the Group repurchases its own shares, the amount of the consideration paid is recognized as a deduction from equity and classified as treasury shares. The profits or losses from the purchase, disposal, reissue, or retirement of treasury shares are directly recognized in equity being as transaction with owners.

Hybrid bond

(21)    Hybrid bond

The Group recognizes a financial instrument issued by the Group as an equity instrument if it does not include contractual obligation to deliver financial assets including cash to the counter party.

Share-based Payment

(22)    Share-based Payment

For equity-settled share-based payment transaction, if the fair value of the goods or services received cannot be reliably estimated, the Group measures their value indirectly by reference to the fair value of the equity instruments granted. Related expense, with a corresponding increase in capital surplus and others is recognized over the vesting period of the awards. The amount recognized as an expense is adjusted to reflect the number of awards for which the related service and non-market performance conditions are expected to be met, such that the amount ultimately recognized is based on the number of awards that meet the related service and non-market performance conditions at the vesting date.

Revenue

(23)    Revenue

Revenue from the sale of goods, rendering of services or use of the Group assets is measured at the fair value of the consideration received or receivable. Returns, trade discounts and volume rebates are recognized as a reduction of revenue.

When two or more revenue generating activities or deliverables are sold under a single arrangement, each deliverable that is considered to be a separate unit of account is accounted for separately. The allocation of consideration from a revenue arrangement to its separate units of account is based on the relative fair values of each unit.

(i)    Services rendered

Revenue from cellular services consists of revenue from basic charges, voice charges, data charges, data-roaming services and interconnection charges. Such revenues are recognized as services are performed.

Revenue from fixed-line services includes domestic and long distance call charges, international phone connection charges, and broadband internet services. Such revenues are recognized as the related services are performed.

Revenue from other services rendered is recognized in profit or loss in proportion to the stage of completion of the transaction at the reporting date. The stage of completion is assessed by reference to surveys of work performed.

(ii)    Goods sold

Revenue is recognized when persuasive evidence exists, usually in the form of an executed sales agreement, that the significant risks and rewards of ownership have been transferred to the buyer, recovery of the consideration is probable, the associated costs and possible return of goods can be estimated reliably, there is no continuing management involvement with the goods, and the amount of revenue can be measured reliably.

(iii)    Commission revenue

In connection with the commission revenue from e-commerce services with following characteristics, the Group has determined that it is acting as an agent.

• The Group does not bear inventory risk or have responsibility for the delivery goods;

• All of the credit risks are borne by suppliers of goods though the Group collects the proceeds from end customers on behalf of the suppliers; and

• The Group has no latitude in establishing prices regarding goods sold in e-commerce.

(iv)    Customer loyalty programs

For customer loyalty programs, the fair value of the consideration received or receivable in respect of the initial sale is allocated between the award credits and the other components of the sale. The amount allocated to the award credits is estimated by reference to the fair value of the services to be provided with respect to the redeemable award credits. The fair value of the services to be provided with respect to the redeemable portion of the award credits granted to the customers in accordance with customer loyalty programs is estimated taking into account the expected redemption rate and timing of the expected redemption. Considerations allocated to the award credits are deferred and revenue is recognized when the award credits are recovered and the Group performs its obligation to provide the service. The amount of revenue recognized is based on the relative size of the total award credits that are expected to be redeemed and the redeemed award credits in exchange for services.

Operating profit

(24)    Operating profit

Operating profit is the result generated from the continuing principal revenue producing activities of the Group as well as other income and expenses related to operating activities. Operating profit excludes net finance costs, share of profit of equity accounted investees and income taxes.

Finance income and finance costs

(25)    Finance income and finance costs

Finance income comprises interest income on funds invested (including available-for-sale financial assets), dividend income, gains on disposal of available-for-sale financial assets, changes in fair value of financial assets at fair value through profit or loss, and gains on hedging instruments that are recognized in profit or loss. Interest income is recognized as it accrues in profit or loss, using the effective interest rate method. Dividend income is recognized in profit or loss on the date that the Group’s right to receive payment is established.

Finance costs comprise interest expense on borrowings, changes in fair value of financial assets at fair value through profit or loss, and losses on hedging instruments that are recognized in profit or loss. Interest expense on borrowings and debentures are recognized in profit or loss using the effective interest rate method.

Income taxes

(26)    Income taxes

Income tax expense comprises current and deferred tax. Current tax and deferred tax are recognized in profit or loss except to the extent that it relates to a business combination, or items recognized directly in equity or in other comprehensive income.

The Group pays income tax in accordance with the tax-consolidation system which applies to the Parent Company and wholly owned subsidiaries.

(i)    Current tax

In accordance with the tax-consolidation system, the Parent Company calculates current taxes for the Parent Company and its wholly owned domestic subsidiaries and recognizes the income tax payable as current tax liabilities of the Parent Company. Current tax is the expected tax payable or receivable on the taxable profit or loss for the year, using tax rates enacted or substantively enacted at the end of the reporting period and includes interests and fines related to income taxes paid or payable. The taxable profit is different from the accounting profit for the period since the taxable profit is calculated excluding the temporary differences, which will be taxable or deductible in determining taxable profit (tax loss) of future periods, and non-taxable or non-deductible items from the accounting profit.

(ii)    Deferred tax

Deferred tax is recognized, using the asset-liability method, in respect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for taxation purposes. The Group recognizes a deferred tax liability for all taxable temporary differences, except for the difference associated with investments in subsidiaries and associates that the Group is able to control the timing of the reversal of the temporary difference and it is probable that the temporary difference will not reverse in the foreseeable future. The Group recognizes a deferred tax asset for all deductible temporary differences to the extent that it is probable that the temporary difference will reverse in the foreseeable future and taxable profit will be available against which the temporary difference can be utilized.

A deferred tax asset is recognized for the carryforward of unused tax losses and unused tax credits to the extent that it is probable that future taxable profit will be available against which the unused tax losses and unused tax credits can be utilized. Future taxable profit is dependent on the reversal of taxable temporary differences. If there are insufficient taxable temporary differences to recognize the deferred tax asset, the business plan of the Group and the reversal of existing temporary differences are considered in determining the future taxable profit.

The Group reviews the carrying amount of a deferred tax asset at the end of each reporting period and reduces the carrying amount to the extent that it is no longer probable that sufficient taxable profit will be available to allow the benefit of part or all of that deferred tax asset to be utilized.

Deferred tax assets and liabilities are measured at the tax rates that are expected to apply to the period when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period. The measurement of deferred tax liabilities and deferred tax assets reflects the tax consequences that would follow from the manner in which the Group expects, at the end of the reporting period, to recover or settle the carrying amount of its assets and liabilities.

Deferred tax assets and liabilities are offset only if there is a legally enforceable right to offset the related current tax liabilities and assets, and they relate to income taxes levied by the same tax authority and they are intended to be settled current tax liabilities and assets on a net basis. Income tax expense in relation to dividend payments is recognized when liabilities relating to the dividend payments are recognized.

Earnings per share

(27)    Earnings per share

The Group presents basic and diluted earnings per share (EPS) data for its ordinary shares. Basic EPS is calculated by dividing the profit or loss attributable to ordinary shareholders of the Parent Company by the weighted average number of ordinary shares outstanding during the period, adjusted for own shares held. Diluted EPS is determined by adjusting the profit or loss attributable to ordinary shareholders and the weighted average number of ordinary shares outstanding, adjusted for own shares held, for the effects of all dilutive potential ordinary shares, which comprise share options granted to employees, if any.

Standards issued but not yet effective

(28)    Standards issued but not yet effective

The following new standards are effective for annual periods beginning after January 1, 2017 and earlier application is permitted; however, the Group has not early adopted the following new standards in preparing these financial statements.

1)    IFRS 9, Financial Instruments

IFRS 9, published in July 2014 which will replace the IAS 39 Financial Instruments: Recognition and Measurement, is effective for annual periods beginning on or after January 1, 2018, with early adoption permitted. The Group currently plans to apply IFRS 9 in the period beginning on January 1, 2018.

IFRS 9 will be applied retrospectively with exemption allowing the Group not to restate comparative information for prior periods with respect to classification and measurement including impairment changes. The Group will recognize any difference on the measurement of financial assets and liabilities in the opening balance of retained earnings of the year beginning January 1, 2018. In the case of hedge accounting, the prospective application is allowed except for those specified in IFRS 9 such as accounting for the time value of options and the forward element of forward contracts which requires retrospective application.

Key features of IFRS 9 includes new classification and measurement approach for financial assets that reflects the business model in which assets are managed and their cash flow characteristics, impairment model based on changes in expected credit losses, and new approach to hedge qualification and methods for assessing hedge effectiveness.

To ensure smooth implementation of IFRS 9, the Group needs to assess the financial impact of adopting IFRS 9, to formulate the accounting policy, and to design, implement and enhance the accounting system and related controls. The expected quantitative impact of adopting IFRS 9 on the Group’s financial statements cannot be reliably estimated because it will be dependent on the financial instruments that the Group holds and economic conditions at that time as well as accounting elections and judgments that it will make in the future.

Based on the circumstances and information available as of December 31, 2017, the Group preliminary assessed the financial impact on its consolidated financial statements resulting from the adoption of IFRS 9. The results of the preliminary assessment are as follows. The results are subject to change according to additional information available in subsequent period.

i)    Classification and measurement of financial assets

Classification of financial assets under IFRS 9 is driven by the entity’s business model for managing financial assets and their contractual cash flows. This contains three principal classification categories: financial assets measured at amortized cost, fair value through other comprehensive income (FVOCI) and fair value through profit or loss (FVTPL). Derivatives embedded in contracts where the host is a financial asset are never bifurcated. Instead, the hybrid financial instrument as a whole is assessed for classification. Details of the classification based on business models and contractual cash flows are as follows:

	Contractual cash flow characteristics
Business model assessment(*1)	Solely payments of principal and interest	Others
Hold to collect contractual cash flows	Amortized cost(*2)	FVTPL-measured at fair value(*3)
Hold to collect contractual cash flows and sell financial assets	FVOCI- measured at fair value(*2)
Hold to sell financial assets and others	FVTPL-measured at fair value

(*1) The business model is expected to be assessed at portfolio level.

(*2) To eliminate or significantly reduce the accounting mismatch, the Group may irrevocably designate a financial asset as measured at FVTPL using the fair value option at initial recognition.

(*3) Equity instruments that are not held for trading may be irrevocably designated as FVOCI using the fair value option. This election will be made on an investment-by-investment basis.

As new classification requirements for financial assets under IFRS 9 are more stringent than requirements under IAS 39, the adoption of the new standard may result in increase in financial assets designated as FVTPL and higher volatility in profit or loss of the Group. As of December 31, 2017, the Group’s financial assets consist of ￦6,176,575 million of loans and receivables, ￦934,390 million of available-for-sale financial assets, and ￦328,314 million of financial assets at fair value through profit or loss.

A financial asset is measured at amortized cost under IFRS 9 if the asset is held by the Group to collect its contractual cash flows and the asset’s contractual cash flows represent solely payments of principal and interest. As of December 31, 2017, the Group has ￦6,176,575 million of loans and receivables measured at amortized cost.

Based on preliminary assessment, most of the Group’s loans and receivables are held to collect their contractual cash flows and the asset’s contractual cash flows represent solely payments of principal and interest. Though some are held for collecting the asset’s contractual cash flows and sale, management does not expect this to have a significant impact due to the short term nature of the receivables.

A financial asset is measured at FVOCI under IFRS 9 if the objective of the business model is achieved both by collecting contractual cash flows and selling financial assets; and the asset’s contractual cash flows represent solely payments of principal and interest. As of December 31, 2017, the Group has ￦19,928 million of debt instruments classified as available-for-sale financial assets.

Most of the debt instruments held by the Group classified as available-for-sale financial assets are expected to be classified as financial assets measured at FVOCI upon adoption IFRS 9 as at January 1, 2018. Therefore, management does not expect there to be a significant impact.

Under IFRS 9, equity instruments that are not held for trading may be irrevocably designated as FVOCI on initial recognition with no recycling of amounts from OCI to profit and loss. As of December 31, 2017, the Group has ￦914,462 million of available-for-sale equity instruments.

As the Group plans to classify the equity instruments with long-term investment purposes to financial assets measured at FVOCI under IFRS 9, the Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements except no recycling of amounts from OCI to profit and loss is allowed.

All other financial assets are measured at FVTPL. As of December 31, 2017, the Group has ￦97,003 million of debt instruments classified as financial assets at FVTPL.

Most of the financial assets classified as FVTPL under IAS 39 of the Group are expected to be designated as financial assets measured at FVTPL under IFRS 9. Therefore, the Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements upon adoption of IFRS 9 as at January 1, 2018.

ii)    Classification and measurement of financial liabilities

Under IFRS 9, for the financial liabilities designated as FVTPL using the fair value option, the element of gains or losses attributable to changes in the own credit risk should normally be recognized in OCI, with the remainder recognized in profit or loss. These amounts recognized in OCI are not recycled to profit or loss even when the liability is derecognized. However, if presentation of the fair value change in respect of the liability’s credit risk in OCI results in or enlarges an accounting mismatch in profit or loss, gains and losses are entirely presented in profit or loss.

Adoption of IFRS 9 may result in decrease in profit or loss, since the amount of fair value changes that is attributable to changes in the credit risk of the liability will be presented in OCI.

As of December 31, 2017, the Group’s total financial liability amounts to ￦12,725,704 million, among which the financial liabilities designated as FVTPL using fair value option amount to ￦60,278 million.

As of December 31, 2017, most of the financial liabilities designated as FVTPL of the Group have short-term maturities with no significant changes in their credit risks. The Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements upon adoption of IFRS 9 as of January 1, 2018.

iii)    Impairment: financial assets and contract assets

The current impairment requirements under IAS 39 are based on an ‘incurred loss model’, where the impairment exists if there is objective evidence as a result of one or more events that occurred after the initial recognition of an asset. However, IFRS 9 replaces the incurred loss model in IAS 39 with an ‘expected credit loss model’ which applies to debt instruments measured at amortized cost or at fair value through other comprehensive income.

Under IFRS 9, the Group should recognize a loss allowance or provision at an amount equal to 12-month expected credit losses or lifetime expected credit losses for financial assets determined by the extent of probable credit deterioration since initial recognition as explained below. Therefore, the new impairment requirements are expected to result in earlier recognition of credit losses compared to the incurred loss model of IAS 39.

Stages(*1)		Loss allowances
Stage 1	No significant increase in credit risk since initial recognition(*2)	Loss allowances are determined for the amount of the expected credit losses that result from default events that are possible within 12 months after the reporting date.
Stage 2	Significant increase in credit risk since initial recognition	Loss allowances are determined for the amount of the expected credit losses that result from all possible default events over the expected life of the financial instrument.
Stage 3	Objective evidence of credit risk impairment

(*1) Under IFRS 15, Revenue from Contracts with Customers (see note 4 (28) (2)), for trade receivables and contract assets arising with no significant credit risk, loss allowances are recognized at an amount equal to lifetime expected credit losses. However, for trade receivables and contract assets with a significant financing component arising under IFRS 15, the Group may choose as its accounting policy to recognize loss allowances at an amount equal to lifetime expected credit losses. In addition, for receivables under lease arrangement, the Group may choose to recognize loss allowances at an amount equal to lifetime expected credit losses. The Group expects to perform the analysis on whether there was a significant increase in credit risk on collective basis instead of on individual instrument basis. In addition, when information that is more forward-looking than past due status is not available without undue cost or effort, the Group expects to use past due information to determine whether there have been significant increases in credit risk since initial recognition.

(*2) The Group may determine that a financial asset’s credit risk has not increased significantly if the asset has low credit risk at the reporting date.

IFRS 9 allows the Group to only recognize the cumulative changes in lifetime expected credit losses since initial recognition as a loss allowance for purchased or originated credit-impaired financial assets at the reporting date. As of December 31, 2017, the Group has ￦6,176,575 million of debt instrument financial assets measured at amortized cost and ￦362,171 million as loss allowances for these assets. The Group’s preliminary assessment did not indicate any material impact on the Group’s consolidated financial statements upon adoption of IFRS 9 on January 1, 2018.

iv)    Hedge accounting

IFRS 9 maintains the mechanics of hedge accounting from those in IAS 39. However, IFRS 9 replaces existing rule-based requirements under IAS 39 that are complex and difficult to apply with principle based requirement focusing more on the Group’s risk management purposes and procedures. Under IAS 9, more hedging instruments and hedged items are permitted and 80%-125% effectiveness requirement is removed.

By complying with the hedging rules in IFRS 9, the Group may apply hedge accounting for transactions that currently do not meet the hedging criteria under IAS 39 thereby reducing volatility in profit or loss. As of December 31, 2017, the Group recognized the total amount of ￦2,026,434 million as hedged liabilities that applied hedge accounting and changes in fair value of cash flow hedge in the amount of ￦73,828 million was recognized in OCI for the year ended December 31, 2017.

Upon initial application of IFRS 9, the Group may choose as its accounting policy to continue to apply hedge accounting requirements under IAS 39 instead of the requirements in IFRS 9.

The Group is yet to decide on its accounting policy whether to continuously apply the hedge accounting requirements of IAS 39 instead of the requirements in IFRS 9 when initially applying IFRS 9. The Group designates derivatives such as currency swaps as hedging instruments to hedge the risk of variability in cash flows associated with the foreign currency debentures and borrowings. As the Group’s hedging instruments as of December 31, 2017 satisfy the hedge requirements of retrospective testing (80~125%) under IAS 39, the adoption of IFRS 9 is not expected to have material impact on the Group’s consolidated financial statements.

2)    IFRS 15, Revenue from Contracts with Customers

IFRS 15, Revenue from Contracts with Customers, published in May 2014 is effective for annual periods beginning on or after January 1, 2018, with early adoption permitted. It replaces existing revenue recognition guidance, including IAS 18, Revenue, IAS 11, Construction Contracts, SIC 31, Revenue: Barter Transactions Involving Advertising Services, International Financial Reporting Interpretations Committee (“IFRIC”) 13, Customer Loyalty Programs, IFRIC 15, Agreements for the Construction of Real Estate, and IFRIC 18, Transfers of Assets from Customers. The Group plans to adopt IFRS 15 on January 1, 2018. The Group plans to apply IFRS 15 by recognizing the cumulative effect of initially applying the IFRS 15 as an adjustment to the opening balance of retained earnings (or other component of equity, as appropriate) of the year beginning January 1, 2018. The Group elected to apply IFRS 15 retrospectively only to contracts that are not completed contracts at the date of initial application (January 1, 2018) using the transition method permitted by IFRS 15.

IAS 18 provides separate revenue recognition criteria by transaction type which include sale of goods, rendering of services, and use of entity assets by others yielding interest, royalties and dividends. However, IFRS 15 introduces a five-step model for revenue recognition that focuses on the ‘transfer of control’ rather than the ‘transfer of risks and rewards’. The steps in five-step model are as follows:

• identification of the contract with a customer;

• identification of the performance obligations in the contract;

• determination of the transaction price;

• allocation of the transaction price to the performance obligations in the contract; and

• recognition of revenue when (or as) the entity satisfies a performance obligation.

The Group performed evaluation and identified necessary changes to its accounting system and related controls based on the understanding of the revenue stream of the Group with the assistance of external information technology and accounting specialists. The Group is assessing the financial impact of the adoption of IFRS 15 on its consolidated financial statements and plans to complete the assessment by March 31, 2018.

Based on the circumstances and information available as of December 31, 2017, the Group preliminarily assessed the financial impact on its consolidated financial statements resulting from the adoption of IFRS 15. The results of the preliminary assessment are as follows. The results are subject to change according to the additional information available to use in subsequent periods.

i) Identification of performance obligations in the contract

A substantial portion of the Group’s revenues are generated from provision of wireless telecommunications services. IFRS 15 requires the Group to evaluate goods or services promised to customers to determine if they are performance obligations other than wireless telecommunications service that should be accounted for separately. The amount and timing of revenue recognition under IFRS 15 may be different from those under IAS 18 depending on the conclusion over the existence of separately identifiable performance obligations and the timing of satisfying each performance obligation.

In the case that the Group provides the wireless telecommunications services and a handset to one customer, the Group will allocate considerations from the customer between handset sale revenue and wireless telecommunications service revenue. The handset sales revenue is recognized when handset is sold and the wireless telecommunications service revenue is recognized as revenue over the period of the contract term as stated in the subscription contract.

ii) Allocate the transaction price to the separate performance obligations

In accordance with IFRS 15, the Group should allocate the transaction price to each performance obligation in a contract in proportion to their stand-alone selling price. The Group plans to use adjusted market assessment method for estimating the stand-alone selling price. However, in some circumstances, ‘expected cost plus a margin’ approach will be used.

The Group is in the progress of assessing the financial impact of allocating the transaction price to each performance obligation in a contract in proportion to their stand-alone selling price for the case where the Group provides the wireless telecommunications services and handset to one customer. Based on the preliminary assessment, the Group expects that wireless telecommunications service revenue will be decreased, while handset sale revenue will be increased upon adoption of IFRS 15.

iii) Incremental costs to acquire a contract

The Group has exclusive contracts with its sales agents to sell the Group’s wireless telecommunications services to subscribers. These agents receive commissions depending on the number of subscribers newly added and retained. The commissions paid to the agents constitute a significant portion of the Group’s operating expenses. Currently, the portion of these commissions that would not have been incurred if there have been no binding contracts with the subscribers are expensed.

Under IFRS 15, for the Group’s incremental costs to acquire a subscription contract, the Group expects to capitalize such amounts and amortized over the expected subscription period estimated based on historical experience. However, as a practical expedient, the Group plans to expense the incremental cost as incurred if the amortization period of the contract acquisition and fulfillment cost is considered to be not longer than one year.

As of December 31, 2017, the Group is assessing the impact of capitalizing the incremental costs associated with obtaining customer contracts. Based on the preliminary assessment, the Group expects commission expenses to decrease, while corresponding assets capitalized (incremental costs of obtaining a contract) and amortization expenses to be recognized and incurred, respectively.

3)    IFRS 16, Leases

IFRS 16, published in January 2016 is effective for annual periods beginning on or after January 1, 2019, with early adoption permitted. IFRS16 replaces existing leases guidance including IAS 17, Leases, IFRIC 4, Determining whether an Arrangement contains a Lease, SIC 15, Operating Leases — Incentives and SIC 27, Evaluating the Substance of Transactions Involving the Legal Form of a Lease.

IFRS 16, at the inception date of a contract and the first implementation of the standard, requires the Group to determine whether a contract is, or contains, a lease unless the Group applies the practical expedient for the existing lease contract at the date of adoption of the standard.

When accounting for lease, lessee and lessor should account for each lease component within the contract as a lease separately from non-lease components of the contract.

Lessee recognizes a right-of-use asset representing its right to use the underlying asset and a lease liability representing its obligation to make lease payments. However, there are optional exemptions for short-term leases and leases of low value items. As a practical expedient, a lessee may elect, by class of underlying asset, not to separate non-lease components from lease components, and instead account for each lease component and any associated non-lease components as a single lease component.

Lessor accounting remains similar to the current standard IAS 17. For a sale and leaseback arrangement, IFRS 16 requires the Group to apply the requirements for determining when a performance obligation is satisfied in IFRS 15 to determine whether the transfer of an asset is accounted for as a sale of that asset. However, sale and leaseback arrangements entered into before the adoption of IFRS 16 may not be reassessed.

i) Lease accounting for lessees

As a lessee, the Group can either apply the IFRS 16 using a full retrospective approach; or modified retrospective approach. The full retrospective approach requires the Group to retrospectively apply the new standard to each prior reporting period presented, while modified retrospective approach requires the lessee to recognize the cumulative effect of initial application at the date of initial application of the new leases standard.

ii) Lease accounting for lessors

In case where the Group is an intermediate lessor, the Group should reassess subleases that were classified as operating leases applying IAS 17 and are ongoing at the date of initial application, whether each sublease should be classified as an operating lease or a finance lease applying IFRS 16. For subleases that were classified as operating leases applying IAS 17 but finance leases applying IFRS 16, the Group should accounts for such sublease as a new finance lease entered into at the date of initial application of IFRS 16.

The Group plans to update its accounting system and related controls and complete the assessment of impact on its consolidated financial statements resulting from the adoption of IFRS 16 by December 31, 2018.

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Reporting Entity (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Total issued shares held by shareholders

The Parent Company’s common shares and depositary receipts (DRs) are listed on the Stock Market of Korea Exchange, the New York Stock Exchange and the London Stock Exchange. As of December 31, 2017, the Parent Company’s total issued shares are held by the following shareholders:

	Number of shares		Percentage of total shares issued(%)
SK Holdings Co., Ltd.		20,363,452		25.22
National Pension Service		7,392,350		9.16
Institutional investors and other minority shareholders		42,853,358		53.07
Treasury shares		10,136,551		12.55
Total number of shares		80,745,711		100.00

List of subsidiaries

The list of subsidiaries as of December 31, 2017 and 2016 is as follows:

				Ownership (%)(*1)
Subsidiary		Location	Primary business	Dec. 31, 2017		Dec. 31, 2016
Subsidiaries owned by the Parent Company	SK Telink Co., Ltd.(*2)	Korea	Telecommunication and MVNO service		100.0		85.9
	SK Communications Co., Ltd.(*3)	Korea	Internet website services		100.0		64.5
	SK Broadband Co., Ltd	Korea	Telecommunication services		100.0		100.0
	PS&Marketing Corporation	Korea	Communications device retail business		100.0		100.0
	SERVICEACE Co., Ltd.	Korea	Customer center management service		100.0		100.0
	SERVICE TOP Co., Ltd.	Korea	Customer center management service		100.0		100.0
	Network O&S Co., Ltd.	Korea	Base station maintenance service		100.0		100.0
	SK Planet Co., Ltd.	Korea	Telecommunication service		98.1		98.1
	IRIVER LIMITED(*4, 5)	Korea	Manufacturing digital audio players and other portable media devices.		45.9		48.9
	SK Telecom China Holdings Co., Ltd.	China	Investment		100.0		100.0
	SK Global Healthcare Business Group, Ltd.	Hong Kong	Investment		100.0		100.0
	SKT Vietnam PTE. Ltd.	Singapore	Telecommunication service		73.3		73.3
	SKT Americas, Inc.	USA	Information gathering and consulting		100.0		100.0
	YTK Investment Ltd.	Cayman Islands	Investment association		100.0		100.0
	Atlas Investment	Cayman Islands	Investment association		100.0		100.0
	Entrix Co., Ltd.(*6)	Korea	Cloud streaming services		—		100.0
	SK techx Co., Ltd.	Korea	System software development and supply		100.0		100.0
	One Store Co., Ltd.	Korea	Telecommunication services		65.5		65.5
Subsidiaries owned by SK Planet Co., Ltd.	SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)	Korea	Data base and internet website service		100.0		100.0
	SK Planet Japan, K. K.(*5)	Japan	Digital contents sourcing service		79.5		100.0
	SK Planet Global PTE. Ltd.	Singapore	Digital contents sourcing service		100.0		100.0
	SKP GLOBAL HOLDINGS PTE. LTD.	Singapore	Investment		100.0		100.0
	SKP America LLC.	USA	Digital contents sourcing service		100.0		100.0
	shopkick Management Company, Inc.	USA	Investment		100.0		100.0
	shopkick, Inc.	USA	Reward points-based in-store shopping app development		100.0		100.0
	Planet11 E-commerce Solutions India Pvt. Ltd.(*6)	India	Electronic commerce platform service		—		99.0
	11street (Thailand) Co., Ltd.	Thailand	Electronic commerce		100.0		100.0
	Hello Nature Ltd.	Korea	Retail of agro-fisheries and livestock		100.0		100.0
Subsidiaries owned by IRIVER LIMITED	iriver Enterprise Ltd.	Hong Kong	Management of Chinese subsidiary		100.0		100.0
	iriver Inc.	USA	Marketing and sales in North America		100.0		100.0
	iriver China Co., Ltd.	China	Sales and manufacturing MP3,4 in China		100.0		100.0
	Dongguan iriver Electronics Co., Ltd.	China	Sales and manufacturing e-book in China		100.0		100.0
	groovers JP Ltd.	Japan	Digital music contents sourcing and distribution service		100.0		100.0
	S.M. LIFE DESIGN COMPANY JAPAN INC.(*6)	Japan	Selling of goods in Japan		100.0		—
	S.M. Mobile Communications JAPAN Inc.(*6)	Japan	Digital contents service		100.0		—
Subsidiaries owned by SK Telink Co., Ltd.	NSOK Co., Ltd. (formerly, Neosnetworks Co., Ltd.)(*7)	Korea	Guarding of facilities		100.0		100.0
Subsidiaries owned by SK techx Co., Ltd.	K-net Culture and Contents Venture Fund	Korea	Capital investing in startups		59.0		59.0
Subsidiaries owned by SK Broadband Co., Ltd.	Home & Service Co., Ltd.(*6)	Korea	Operation of information and communication facility		100.0		—
	SK stoa Co., Ltd.(*6)	Korea	Other telecommunication retail business		100.0		—
Others(*8)	SK Telecom Innovation Fund, L.P.	USA	Investment		100.0		100.0
	SK Telecom China Fund I L.P.	Cayman Islands	Investment		100.0		100.0
	Stonebridge Cinema Fund(*6)	Korea	Capital investing in startups		—		60.0

(*1) The ownership interest represents direct ownership interest in subsidiaries either by the Parent Company or subsidiaries of the Parent Company.

(*2) On September 28, 2017, the board of directors of the Parent Company resolved to acquire the shares of SK Telink Co., Ltd. held by the non-controlling shareholders of SK Telink Co., Ltd. on December 14, 2017 at ￦270,583 per share in cash. The Parent Company paid ￦35,281 million in cash, in aggregate, and wholly owns SK Telink Co., Ltd. as of December 31, 2017.

(*3) On November 24, 2016, the board of directors of the Parent Company resolved to acquire all of the shares of SK Communications Co., Ltd. held by the non-controlling shareholders of SK Communications Co., Ltd. on February 7, 2017 at ￦2,814 per share in cash. The Parent Company paid ￦41,550 million in cash ,in aggregate, and wholly owns SK Communications Co., Ltd. as of December 31, 2017.

(*4) Although the Group has less than 50% of the voting rights of IRIVER LIMITED, the Group is considered to have control over IRIVER LIMITED since the Group holds significantly more voting rights than any other vote holder or organized group of vote holders, and the other shareholdings are widely dispersed.

(*5) The ownership interest changed due to the non-proportional capital increase during the year ended December 31, 2017.

(*6) Details of changes in consolidation scope for the year ended December 31, 2017 are presented in Note 1-(4).

(*7) During the year ended December 31, 2017, Neosnetworks Co., Ltd. changed its name to NSOK Co., Ltd.

(*8) Others are owned together by Atlas Investment and one other subsidiary of the Parent Company.

Condensed financial information of the significant subsidiaries

Condensed financial information of the significant subsidiaries as of and for the year ended December 31, 2017 is as follows:

(In millions of won)	As of December 31, 2017						2017
Subsidiary	Total assets		Total liabilities		Total equity		Revenue		Profit (loss)
SK Telink Co., Ltd.	￦	455,685		104,727		350,958		389,944		32,728
SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)		113,515		62,795		50,720		193,256		1,249
SK Communications Co., Ltd.		90,923		28,410		62,513		47,546		(35,454	)
SK Broadband Co., Ltd.		3,802,349		2,616,317		1,186,032		3,050,083		32,030
K-net Culture and Contents Venture Fund		250,747		35,900		214,847		—		196,250
PS&Marketing Corporation		506,883		288,881		218,002		1,766,142		391
SERVICEACE Co., Ltd.		77,681		45,501		32,180		197,408		2,599
SERVICE TOP Co., Ltd.		65,406		41,860		23,546		186,117		3,309
Network O&S Co., Ltd.		87,000		45,248		41,752		255,841		6,283
SK Planet Co., Ltd.		1,534,866		920,677		614,189		1,082,685		(513,667	)
IRIVER LIMITED(*)		130,878		17,204		113,674		69,452		(14,092	)
SKP America LLC.		412,251		—		412,251		—		(57	)
SK techx Co., Ltd.		237,700		41,561		196,139		195,948		26,827
One Store Co., Ltd.		104,891		39,874		65,017		115,596		(27,254	)
Home & Service Co., Ltd.		83,698		38,350		45,348		141,739		11
shopkick Management Company, Inc.		338,650		—		338,650		—		(238	)
shopkick, Inc.		37,336		32,219		5,117		48,836		(25,249	)

(*) The condensed financial information of IRIVER LIMITED is consolidated financial information including iriver Enterprise Ltd. and six other subsidiaries of IRIVER LIMITED. Information for the other subsidiaries in the above summary is based on their separate financial statements.

Condensed financial information of the significant subsidiaries as of and for the year ended December 31, 2016 is as follows:

(In millions of won)	As of December 31, 2016						2016
Subsidiary	Total assets		Total liabilities		Total equity		Revenue		Profit (loss)
SK Telink Co., Ltd.	￦	440,956		122,741		318,215		406,930		61,585
SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)		107,768		56,596		51,172		173,816		4,958
SK Communications Co., Ltd.		128,233		31,592		96,641		58,154		(20,411	)
SK Broadband Co., Ltd.		3,523,494		2,376,429		1,147,065		2,942,976		21,526
PS&Marketing Corporation		546,803		328,846		217,957		1,679,735		11,908
SERVICEACE Co., Ltd.		67,735		40,014		27,721		199,828		3,605
SERVICE TOP Co., Ltd.		59,004		39,121		19,883		186,740		3,971
Network O&S Co., Ltd.		69,774		35,798		33,976		218,917		3,755
SK Planet Co., Ltd.(*1)		1,935,663		834,151		1,101,512		1,177,323		(30,959	)
IRIVER LIMITED(*2)		50,075		11,941		38,134		52,328		(9,987	)
SKP America LLC.		439,209		—		439,209		—		1,226
SK techx Co., Ltd.		212,819		52,563		160,256		193,396		28,213
One Store Co., Ltd.		134,207		41,738		92,469		106,809		(22,161	)
shopkick Management Company, Inc.		354,627		—		354,627		—		(85	)
shopkick, Inc.		37,947		34,024		3,923		45,876		(27,149	)

(*1) The separate financial information of SK Planet Co., Ltd. includes pre-merger income and expenses of Commerce Planet Co., Ltd. prior to the merger date of February 1, 2016.

(*2) The condensed financial information of IRIVER LIMITED is consolidated financial information including iriver Enterprise Ltd. and five other subsidiaries of IRIVER LIMITED.

Condensed financial information of the significant subsidiaries as of and for the year ended December 31, 2015 is as follows:

(In millions of won)	As of December 31, 2015							2015
Subsidiary	Total assets		Total liabilities		Total equity			Revenue		Profit (loss)
SK Telink Co., Ltd.	￦	309,955		113,878		196,077			431,368		55,781
SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)		89,452		42,414		47,038			143,255		5,549
SK Communications Co., Ltd.		152,496		35,014		117,482			80,147		(14,826	)
SK Broadband Co., Ltd.		3,291,707		2,170,484		1,121,223			2,731,344		10,832
PS&Marketing Corporation		509,580		300,364		209,216			1,791,944		4,835
SERVICEACE Co., Ltd.		65,424		34,240		31,184			206,338		2,778
SERVICE TOP Co., Ltd.		61,897		38,482		23,415			197,092		4,396
Network O&S Co., Ltd.		77,426		48,069		29,357			210,676		6,466
SK Planet Co., Ltd.		2,406,988		784,631		1,622,357			1,624,630		(75,111	)
IRIVER LIMITED(*)		60,434		12,377		48,057			55,637		635
SKP America LLC.		380,141		—		380,141			—		791
Entrix Co., Ltd.		30,876		3,186		27,690			4,895		(1,826	)
shopkick Management Company, Inc.		306,248		7		306,241			7		(2,455	)
shopkick, Inc.		25,388		32,243		(6,855	)		33,851		(52,390	)

(*) The condensed financial information of IRIVER LIMITED is consolidated financial information including iriver Enterprise Ltd. and five other subsidiaries of IRIVER LIMITED.

(4)    Changes in subsidiaries

The list of subsidiaries that were newly included in consolidation during the year ended December 31, 2017 is as follows:

Subsidiary	Reason
S.M. LIFE DESIGN COMPANY JAPAN INC. (Refer to Note10)	Acquired by IRIVER LIMITED
S.M. Mobile Communications JAPAN Inc. (Refer to Note10)	Acquired by IRIVER LIMITED
Home & Service Co., Ltd.	Established by SK Boradband Co., Ltd.
SK stoa Co., Ltd.	Established by SK Boradband Co., Ltd.

The list of subsidiaries that were excluded from consolidation during the year ended December 31, 2017 is as follows:

Subsidiary	Reason
Entrix Co., Ltd.	Merged into SK techx Co., Ltd. during the year ended December 31, 2017.
Planet11 E-commerce Solutions India Pvt. Ltd.	Disposed during the year ended December 31, 2017.
Stonebridge Cinema Fund	Liquidated during the year ended December 31, 2017.

Information of significant non-controlling interests of the group

(5)    The information of significant non-controlling interests of the Group as of and for the years ended December 31, 2017, 2016 and 2015 are as follows. There were no dividends paid during the years ended December 31, 2017, 2016 and 2015 by subsidiaries of which non-controlling interests are significant.

(In millions of won)
	K-net Culture and Contents Venture Fund			IRIVER LIMITED			One Store Co., Ltd.
Ownership of non-controlling interests (%)		41.00			54.10			34.46
	As of December 31, 2017
Current assets	￦	625			74,873			76,810
Non-current assets		250,122			56,005			28,081
Current liabilities		(35,900	)		(9,563	)		(38,547	)
Non-current liabilities		—			(7,641	)		(1,327	)
Net assets		214,847			113,674			65,017
Carrying amount of non-controlling interests		88,087			63,382			22,405
	2017
Revenue	￦	—			69,452			115,596
Profit (loss) for the year		196,250			(14,092	)		(27,254	)
Total comprehensive profit (loss)		201,693			(14,278	)		(27,452	)
Profit (loss) attributable to non-controlling interests		80,463			(7,438	)		(9,392	)
Net cash provided by (used in) operating activities	￦	(7	)		(7,553	)		13,912
Net cash used in investing activities		(600	)		(45,002	)		(2,000	)
Net cash provided by (used in) financing activities		—			64,571			(7	)
Net increase (decrease) in cash and cash equivalents		(607	)		12,016			11,905

(In millions of won)
	SK Communications Co., Ltd.			One Store Co., Ltd.
Ownership of non-controlling interests (%)		35.46			34.46
	As of December 31, 2016
Current assets	￦	81,806			90,414
Non-current assets		46,427			43,793
Current liabilities		(30,098	)		(40,969	)
Non-current liabilities		(1,494	)		(769	)
Net assets		96,641			92,469
Carrying amount of non-controlling interests		34,265			31,863
	2016
Revenue	￦	58,154			106,809
Loss for the year		20,411			22,161
Total comprehensive loss		20,841			22,402
Loss attributable to non-controlling interests		7,240			6,772
Net cash used in operating activities	￦	(4,891	)		(4,447	)
Net cash provided by (used in) investing activities		3,625			(20,796	)
Net cash provided by financing activities		—			51,426
Net increase(decrease) in cash and cash equivalents		(1,266	)		26,183

(In millions of won)
	SK Communications Co., Ltd.
Ownership of non-controlling interests (%)		35.46
	As of December 31, 2015
Current assets	￦	95,662
Non-current assets		56,834
Current liabilities		(33,306	)
Non-current liabilities		(1,708	)
Net assets		117,482
Carrying amount of non-controlling interests		41,659
	2015
Revenue	￦	80,147
Loss for the period		14,826
Total comprehensive loss		16,698
Loss attributable to non-controlling interests		5,254
Net cash used in operating activities	￦	(2,706	)
Net cash provided by investing activities		8,723
Net cash provided by financing activities		—
Net increase in cash and cash equivalents		6,017

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Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Estimated useful lives of the Group's property and equipment

The estimated useful lives of the Group’s property and equipment are as follows:

	Useful lives (years)
Buildings and structures		15 ~ 40
Machinery		3 ~ 15
Other property and equipment		2 ~ 10

Estimated useful lives of the Group's intangible assets

The estimated useful lives of the Group’s intangible assets are as follows:

	Useful lives (years)
Frequency usage rights	5 ~ 13
Land usage rights	5
Industrial rights	5, 10
Development costs	3 ~ 5
Facility usage rights	10, 20
Customer relations	3 ~ 7
Other	3 ~ 20

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Operating Segments (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Segment information

(1) Segment information for the years ended December 31, 2017, 2016 and 2015 is as follows:

(In millions of won)
	2017
	Cellular Services		Fixed-line telecommu- nication services		E-commerce Services			Others			Sub-total		Adjustments			Total
Total revenue	￦	14,873,543		3,586,887		1,091,903			788,836			20,341,169		(2,821,156	)		17,520,013
Inter-segment revenue		1,611,408		862,736		47,732			299,280			2,821,156		(2,821,156	)		—
External revenue		13,262,135		2,724,151		1,044,171			489,556			17,520,013		—			17,520,013
Depreciation and amortization		2,390,016		592,877		54,486			60,087			3,097,466		—			3,097,466
Operating profit (loss)		1,714,078		167,515		(267,829	)		(77,138	)		1,536,626		(312,054	)		1,224,572
Gain relating to investments in subsidiaries, associates and joint ventures, net																	2,245,732
Finance income																	366,561
Finance costs																	(433,616	)
Profit before income tax																	3,403,249

(In millions of won)
	2016
	Cellular Services		Fixed-line telecommu- nication services		E-commerce Services			Others			Sub-total		Adjustments			Total
Total revenue	￦	14,635,720		3,349,905		1,177,323			726,374			19,889,322		(2,797,506	)		17,091,816
Inter-segment revenue		1,630,811		698,712		176,007			291,976			2,797,506		(2,797,506	)		—
External revenue		13,004,909		2,651,193		1,001,316			434,398			17,091,816		—			17,091,816
Depreciation and amortization		2,262,363		551,811		68,298			59,414			2,941,886		—			2,941,886
Operating profit (loss)		1,799,127		132,459		(365,194	)		(30,648	)		1,535,744		(232,326	)		1,303,418
Gain relating to investments in subsidiaries, associates and joint ventures, net																	544,501
Finance income																	575,050
Finance costs																	(326,830	)
Profit before income tax																	2,096,139
(In millions of won)
	2015
	Cellular Services		Fixed-line telecommu- nication services		E-commerce Services			Others			Sub-total		Adjustments			Total
Total revenue	￦	14,962,689		3,162,712		1,703,278			410,265			20,238,944		(3,102,210	)		17,136,734
Inter-segment revenue		1,693,411		668,139		643,299			97,361			3,102,210		(3,102,210	)		—
External revenue		13,269,278		2,494,573		1,059,979			312,904			17,136,734		—			17,136,734
Depreciation and amortization		2,174,819		531,106		112,537			26,833			2,845,295		—			2,845,295
Operating profit (loss)		1,678,339		108,252		(6,740	)		(71,845	)		1,708,006		(212,581	)		1,495,425
Gain relating to investments in subsidiaries, associates and joint ventures, net																	786,140
Finance income																	103,900
Finance costs																	(350,100	)
Profit before income tax																	2,035,365

Reconciliation of total segment operating income to consolidated operating profit from continuing operations

(2) Reconciliation of total segment operating income to consolidated operating profit from continuing operations for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)	2017			2016			2015
Total segment operating income	￦	1,536,626			1,535,744			1,708,006
Other operating income:
Gain on disposal of property and equipment and intangible assets		13,991			6,908			7,140
Others(*1)		18,006			59,640			23,795
		31,997			66,548			30,935
Other operating expenses:
Impairment loss on property and equipment and intangible assets		(54,946	)		(24,506	)		(35,845	)
Loss on disposal of property and equipment and intangible assets		(60,086	)		(63,797	)		(21,392	)
Donations		(112,634	)		(96,633	)		(72,454	)
Bad debt for accounts receivable — other		(5,793	)		(40,312	)		(15,323	)
Others(*2)		(110,592	)		(73,626	)		(98,502	)
		(344,051	)		(298,874	)		(243,516	)
Consolidated operating profit from continuing operations	￦	1,224,572			1,303,418			1,495,425

(*1) Others for the year ended December 31, 2016 include ￦25 billion of penalty refund.

(*2) Others for the years ended December 31, 2017, 2016 and 2015 primarily consist of ￦21.4 billion, ￦7.6 billion and ￦29.5 billion of penalties, respectively, and various other expenses with inconsequential amounts.

Since there are no intersegment sales of inventory or depreciable assets, there is no unrealized intersegment profit to be eliminated on consolidation. Domestic revenue for the years ended December 31, 2017, 2016 and 2015 amounts to ￦17,374 billion, ￦16,940 billion and ￦17,083 billion, respectively. Domestic non-current assets (excluding financial assets, investments in associates and joint ventures and deferred tax assets) as of December 31, 2017, 2016 and 2015 amount to ￦15,554 billion, ￦15,949 billion and ￦14,474 billion, and non-current assets outside of Korea amount to ￦257 billion, ￦286 billion and ￦287 billion, respectively.

No single customer contributed 10% or more to the Group’s total sales for the years ended December 31, 2017, 2016 and 2015.

Operating revenue by service type

(3) The Group’s operating revenue by service type is as follows:

(In millions of won)
	2017		2016		2015
Cellular revenue:
Wireless service(*1)	￦	10,638,961		10,582,963		10,720,518
Cellular interconnection		592,754		614,446		710,026
Wireless device sales		1,052,203		922,449		963,354
Miscellaneous(*2)		978,217		885,051		875,380
		13,262,135		13,004,909		13,269,278
Fixed-line telecommunication services revenue:
Fixed line telephone service		316,763		357,754		420,611
Fixed line interconnection		116,070		134,089		57,130
Broadband internet service and advanced media platform service		1,641,645		1,472,776		1,308,789
International calling service		89,412		95,986		99,106
Miscellaneous(*3)		560,261		590,588		608,937
		2,724,151		2,651,193		2,494,573
E-commerce services revenue(*4)		1,044,171		1,001,316		1,059,979
Other revenue:
Portal service(*5)		43,952		54,177		71,812
Miscellaneous(*6)		445,604		380,221		241,092
		489,556		434,398		312,904
Consolidated operating revenue	￦	17,520,013		17,091,816		17,136,734

(*1) Wireless service revenue includes revenue from wireless voice and data transmission services principally derived through monthly plan-based fees, usage charges for outgoing voice calls, usage charges for wireless data services and value-added service fees paid by our wireless subscribers.

(*2) Miscellaneous cellular services revenue includes revenue from IoT solutions as well as other miscellaneous cellular services.

(*3) Miscellaneous fixed-line telecommunication services revenue includes revenues from business communications services (other than fixed-line telephone service) provided by SK Broadband and VoIP services provided by SK Telink

(*4) E-commerce service revenue includes revenues from 11st, open marketplace platform, and other commerce solutions.

(*5) Portal service revenue includes revenues from Nate, and online portal service operated by SK Communications.

(*6) Miscellaneous other revenue includes revenues from hardware business, security business operated by one of the Group’s subsidiaries, NSOK Co., Ltd., marketing and sales solutions business operated by one of the Group’s subsidiaries, SK m&service Co., Ltd., and online open marketplace for mobile applications among other operations.

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Restricted Deposits (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Deposits which are restricted in use

Deposits which are restricted in use as of December 31, 2017 and 2016 are summarized as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Short-term financial instruments(*)	￦	89,850		90,278
Long-term financial instruments(*)		1,222		937
	￦	91,072		91,215

(*) Financial instruments include charitable trust fund established by the Group where profits from the fund are donated to charitable institutions. As of December 31, 2017, the funds cannot be withdrawn before maturity.

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Categories of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Summary of financial assets

(1) Financial assets by category as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Financial assets at fair value through profit or loss		Available- for-sale financial assets		Loans and receivables		Derivatives hedging instrument		Total
Cash and cash equivalents	￦	—		—		1,457,735		—		1,457,735
Financial instruments		—		—		618,002		—		618,002
Short-term investment securities		97,003		47,383		—		—		144,386
Long-term investment securities		—		887,007		—		—		887,007
Accounts receivable — trade		—		—		2,138,755		—		2,138,755
Loans and other receivables(*)		—		—		1,962,083		—		1,962,083
Derivative financial assets		231,311		—		—		21,902		253,213
	￦	328,314		934,390		6,176,575		21,902		7,461,181

(In millions of won)
	December 31, 2016
	Financial assets at fair value through profit or loss		Available- for-sale financial assets		Loans and receivables		Derivatives hedging instrument		Total
Cash and cash equivalents	￦	—		—		1,505,242		—		1,505,242
Financial instruments		—		—		469,705		—		469,705
Short-term investment securities		—		107,364		—		—		107,364
Long-term investment securities		—		828,521		—		—		828,521
Accounts receivable — trade		—		—		2,261,311		—		2,261,311
Loans and other receivables(*)		—		—		1,701,249		—		1,701,249
Derivative financial assets		7,368		—		—		207,402		214,770
	￦	7,368		935,885		5,937,507		207,402		7,088,162

(*) Details of loans and other receivables as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Short-term loans	￦	62,830		58,979
Accounts receivable — other		1,260,835		1,121,444
Accrued income		3,979		2,780
Other current assets		3,927		3,937
Long-term loans		50,874		65,476
Long-term accounts receivable — other		287,048		149,669
Guarantee deposits		292,590		298,964
	￦	1,962,083		1,701,249

Summary of financial liabilities

(2) Financial liabilities by category as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Financial liabilities at fair value through profit or loss		Financial liabilities measured at amortized cost		Derivatives hedging instrument		Total
Accounts payable — trade	￦	—		351,711		—		351,711
Derivative financial liabilities		—		—		39,470		39,470
Borrowings		—		382,817		—		382,817
Debentures(*1)		60,278		7,025,909		—		7,086,187
Accounts payable — other and others(*2)		—		4,865,519		—		4,865,519
	￦	60,278		12,625,956		39,470		12,725,704

(In millions of won)
	December 31, 2016
	Financial liabilities at fair value through profit or loss		Financial liabilities measured at amortized cost		Derivatives hedging instrument		Total
Accounts payable — trade	￦	—		402,445		—		402,445
Derivative financial liabilities		—		—		87,153		87,153
Borrowings		—		175,521		—		175,521
Debentures(*1)		59,600		7,134,606		—		7,194,206
Accounts payable — other and others (*2)		—		4,842,734		—		4,842,734
	￦	59,600		12,555,306		87,153		12,702,059

(*1) Bonds classified as financial liabilities at fair value through profit or loss as of December 31, 2017 and 2016 are structured bonds and they were designated as financial liabilities at fair value through profit or loss in order to eliminate a measurement inconsistency with the related derivatives.

(*2) Details of accounts payable — other and others as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Accounts payable — other	￦	1,867,074		1,767,799
Withholdings		1,736		1,525
Accrued expenses		1,327,906		1,125,816
Current portion of long-term payables — other		302,703		301,773
Long-term payables — other		1,346,763		1,624,590
Other non-current liabilities		19,337		21,231
	￦	4,865,519		4,842,734

Trade and other receivables [member]

Summary of financial assets

(1) Details of trade and other receivables as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Gross amount		Allowances for doubtful accounts			Carrying amount
Current assets:
Accounts receivable — trade	￦	2,365,270		(239,263	)		2,126,007
Short-term loans		63,380		(550	)		62,830
Accounts receivable — other		1,336,247		(75,412	)		1,260,835
Accrued income		3,979		—			3,979
Others		3,927		—			3,927
		3,772,803		(315,225	)		3,457,578
Non-current assets:
Long-term loans		97,635		(46,761	)		50,874
Long-term accounts receivable — other		287,048		—			287,048
Guarantee deposits		292,590		—			292,590
Long-term accounts receivable — trade		12,933		(185	)		12,748
		690,206		(46,946	)		643,260
	￦	4,463,009		(362,171	)		4,100,838

(In millions of won)
	December 31, 2016
	Gross amount		Allowances for doubtful accounts			Carrying amount
Current assets:
Accounts receivable — trade	￦	2,482,502		(241,576	)		2,240,926
Short-term loans		59,526		(547	)		58,979
Accounts receivable — other		1,200,421		(78,977	)		1,121,444
Accrued income		2,780		—			2,780
Others		3,937		—			3,937
		3,749,166		(321,100	)		3,428,066
Non-current assets:
Long-term loans		113,456		(47,980	)		65,476
Long-term accounts receivable — other		149,669		—			149,669
Guarantee deposits		298,964		—			298,964
Long-term accounts receivable — trade		20,637		(252	)		20,385
		582,726		(48,232	)		534,494
	￦	4,331,892		(369,332	)		3,962,560

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Trade and Other Receivables (Tables) - Trade and other receivables [member]

12 Months Ended

Dec. 31, 2017

Changes in allowances for doubtful accounts of trade and other receivables

(2) Changes in allowances for doubtful accounts of trade and other receivables for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Balance at January 1	￦	369,332			344,016
Bad debt expense		40,377			78,132
Write-offs		(70,802	)		(79,891	)
Other		23,264			27,075
Balance at December 31	￦	362,171			369,332

Details of overdue but not impaired, and impaired trade and other receivables

(3) Details of overdue but not impaired, and impaired trade and other receivables as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017						December 31, 2016
	Accounts receivable - trade			Other receivables			Accounts receivable - trade			Other receivables
Neither overdue nor impaired	￦	1,585,714			1,930,261			1,715,966			1,617,349
Overdue but not impaired		29,304			3,113			41,613			5,663
Impaired		763,185			151,432			745,560			205,741
		2,378,203			2,084,806			2,503,139			1,828,753
Allowances for doubtful accounts		(239,448	)		(122,723	)		(241,828	)		(127,504	)
	￦	2,138,755			1,962,083			2,261,311			1,701,249

Aging of overdue but not impaired accounts receivable

(4) The aging of overdue but not impaired accounts receivable as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017				December 31, 2016
	Accounts receivable - trade		Other receivables		Accounts receivable - trade		Other receivables
Less than 1 month	￦	7,150		2,679		11,543		2,838
1 ~ 3 months		1,663		44		9,144		140
3 ~ 6 months		1,576		124		4,643		1
More than 6 months		18,915		266		16,283		2,684
	￦	29,304		3,113		41,613		5,663

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Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Details of inventories

Details of inventories as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017							December 31, 2016
	Acquisition cost		Write-down			Carrying amount		Acquisition cost		Write-down			Carrying amount
Merchandise	￦	251,463		(7,488	)		243,975		232,871		(6,913	)		225,958
Finished goods		1,889		(557	)		1,332		1,931		(363	)		1,568
Work-in-process		1,906		(956	)		950		2,895		(347	)		2,548
Raw materials and supplies		29,395		(3,249	)		26,146		31,141		(1,369	)		29,772
	￦	284,653		(12,250	)		272,403		268,838		(8,992	)		259,846

Amount of the inventory write-downs charged to the consolidated statement of income and write-off of inventories

The amount of the inventory write-downs and write-off of inventories charged to statement of income are as follows:

(In millions of won)
	2017			2016			2015
Charged to cost of products that have been resold	￦	6,079			3,751			1,983
Write-off upon sale		(2,820	)		(1,299	)		(2,095	)

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Investment Securities (Tables)

12 Months Ended

Dec. 31, 2017

Less than 1 year [Member]

Details of investment securities

(1) Details of short-term investment securities as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Beneficiary certificates(*)	￦	144,386		107,364

Later than one year [Member]

Details of investment securities

Details of long-term investment securities as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Equity securities:
Marketable equity securities(*1)	￦	589,202		526,363
Unlisted equity securities etc.(*2)		277,877		295,403
		867,079		821,766
Debt securities:
Investment bonds		19,928		6,755
	￦	887,007		828,521

(*1) During the year ended December 31, 2016, the Group sold 3,793,756 shares of Loen Entertainment, Inc. to Kakao Corp. in exchange for 1,357,367 shares of Kakao Corp. and ￦218,037 million in cash. In connection with the sale of Loen Entertainment shares, the Group recognized gain on disposal of long-term investment securities amounting to ￦314,745 million.

The Group recognized gain on disposal amounting to ￦138,779 million as the Group disposed its entire marketable equity securities of POSCO Co., Ltd. for ￦305,110 million of cash during the year ended December 31, 2016.

In addition, the Group sold 1,357,367 shares of Kakao Corp. in exchange for ￦112,649 million in cash during the year ended December 31, 2017. In connection with the sale of Kakao Corp. shares, the Group recognized loss on disposal of long-term investment securities amounting to ￦35,468 million.

(*2) Unlisted equity securities and equity investments whose fair value cannot be measured reliably are recorded at cost.

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Business Combination (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Considerations paid and assets in succession recognized at the acquisition date

3) Considerations paid and assets and liabilities recognized at the acquisition date are as follows:

(In millions of won)
	S.M. LIFE DESIGN COMPANY JAPAN INC.			S.M. Mobile Communications JAPAN Inc.
Considerations paid:
Cash and cash equivalents	￦	30,000			—
Shares of IRIVER LIMITED		—			24,650
Assets and liabilities acquired:
Cash and cash equivalents	￦	3,434			4,112
Trade and other receivables		1,471			237
Inventories		1,879			—
Property and equipment		4			311
Intangible assets		6,677			7,445
Other assets		—			41
Trade and other payables		(2,563	)		(815	)
Deferred tax liabilities		(2,324	)		—
Other liabilities		(326	)		(154	)
Net assets	￦	8,252			11,177

2) Considerations paid and identifiable assets acquired and liabilities assumed

Considerations paid and assets in succession recognized at the acquisition date are as follows:

(In millions of won)
	2015
Considerations paid and liabilities assumed:
Cash and cash equivalents	￦	13,197
Accounts payable — other		1,858
	￦	15,055
Assets acquired:
Property and equipment	￦	3,208
Intangible assets		8,486
Other assets		1,603
	￦	13,297

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Investments in Associates and Joint Ventures (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Investments in associates and joint ventures accounted for using the equity method

(1) Investments in associates and joint ventures accounted for using the equity method as of December 31, 2017 and 2016 are as follows:

(In millions of won)
		December 31, 2017				December 31, 2016
	Country	Ownership (%)		Carrying amount		Ownership (%)		Carrying amount
Investments in associates:
SK China Company Ltd.(*1)	China		27.3	￦	526,099		9.6	￦	46,354
Korea IT Fund(*2)	Korea		63.3		257,003		63.3		263,850
KEB HanaCard Co., Ltd.(*3)	Korea		15.0		280,988		15.0		265,798
NanoEnTek, Inc.	Korea		28.5		38,718		28.5		39,514
SK Industrial Development China Co., Ltd.(*1)	Hong Kong		—		—		21.0		74,717
SK Technology Innovation Company	Cayman Islands		49.0		42,511		49.0		47,488
HappyNarae Co., Ltd.(*4)	Korea		45.0		21,873		42.5		17,236
SK hynix Inc.	Korea		20.1		8,130,000		20.1		6,132,122
SK MENA Investment B.V.	Netherlands		32.1		13,853		32.1		15,451
SKY Property Mgmt. Ltd.(*1)	Virgin Island		—		—		33.0		263,225
S.M. Culture & Contents Co., Ltd.(*5)	Korea		23.4		64,966		—		—
Xian Tianlong Science and Technology Co., Ltd.	China		49.0		25,891		49.0		25,880
Daehan Kanggun BcN Co., Ltd. and others	—		—		96,479		—		115,181
Sub-total					9,498,381				7,306,816
Investments in joint ventures:
Dogus Planet, Inc.(*6)	Turkey		50.0		13,991		50.0		20,081
PT XL Planet Digital(*7)	Indonesia		—		—		50.0		27,512
Finnq Co., Ltd.(*8)	Korea		49.0		16,474		49.0		24,174
Celcom Planet and others	—		—		9,592		—		25,740
Sub-total					40,057				97,507
Total				￦	9,538,438			￦	7,404,323

(*1) During the year ended December 31, 2017, the Group contributed its shares in SKY Property Mgmt. Ltd. and SK Industrial Development China Co., Ltd., both equity method investees of the Group, to SK China Company Ltd., and participated in SK China Company Ltd.’s rights issue amounting to USD 100,000,000, which resulted in Group’s acquiring 8,101,884 and 2,107,037 shares of SK China Company Ltd., respectively. This investment in associates acquired through this contribution in kind transaction was measured at fair value.

(*2) Investment in Korea IT Fund was classified as investment in associates as the Group does not have control over Korea IT Fund under the contractual agreement with other shareholders.

(*3) This investment was classified as investments in associates as the Group can exercise significant influence through its right to appoint the members of board of directors even though the Group has less than 20% of equity interests.

(*4) The Group acquired 40,000 shares of HappyNarae Co., Ltd. at ￦17,212 per share during the year ended December 31, 2017.

(*5) During the year ended December 31, 2017, the Group subscribed to a third-party allocation of new shares of 22,033,898 by S.M. Culture & Contents Co., Ltd. at ￦65,341 million in cash.

(*6) The investment is held by SK Planet Co., Ltd.

(*7) PT XL Planet Digital was disposed during the year ended December 31, 2017.

(*8) Investment in Finnq Co., Ltd. was classified as investment in joint venture as the Group has joint control pursuant to the agreement with the other shareholders.

Market price of investments in listed associates

(2) The market price of investments in listed associates as of December 31, 2017 and 2016 are as follows:

(In millions of won, except for share data)
	December 31, 2017						December 31, 2016
	Market value per share (in won)		Number of shares		Fair value		Market value per share (in won)		Number of shares		Fair value
NanoEnTek, Inc.	￦	5,950		6,960,445		41,415		5,020		6,960,445		34,941
SK hynix Inc.		76,500		146,100,000		11,176,650		44,700		146,100,000		6,530,670
S.M. Culture & Contents Co., Ltd.		2,700		22,033,898		59,492		—		—		—

Financial information of significant associates

(3) The financial information of significant associates as of December 31, 2017 and 2016 and for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	As of December 31, 2017
	SK hynix Inc.(*)			KEB HanaCard Co., Ltd. (*)			SK China Company Ltd. (*)
Current assets	￦	17,310,444			7,339,492			729,872
Non-current assets		28,108,020			220,258			1,031,647
Current liabilities		8,116,133			1,181,746			81,161
Non-current liabilities		3,481,412			4,861,842			64,717
	2017
Revenue		30,109,434			1,519,607			69,420
Profit for the year		10,642,219			106,352			11,492
Other comprehensive income (loss)		(422,042	)		(984	)		27,190
Total comprehensive income		10,220,177			105,368			38,682

(*) The financial information of SK hynix Inc., KEB HanaCard Co., Ltd., and SK China Company Ltd. are consolidated financial information.

(In millions of won)
	As of December 31, 2016
	SK hynix Inc.(*)		KEB HanaCard Co., Ltd.(*)
Current assets	￦	9,838,982		6,868,387
Non-current assets		22,377,044		239,758
Current liabilities		4,160,849		1,219,327
Non-current liabilities		4,031,647		4,476,979
	2016
Revenue		17,197,975		1,413,077
Profit for the year		2,960,483		75,595
Other comprehensive income (loss)		28,844		(154	)
Total comprehensive income		2,989,327		75,441

(*) The financial information of SK hynix Inc. and KEB HanaCard Co., Ltd. are consolidated financial information.

(In millions of won)
	SK hynix Inc.		KEB HanaCard Co., Ltd.
	2015
Revenue	￦	18,797,998		1,472,830
Profit for the year		4,323,595		10,119
Other comprehensive income (loss)		40,215		(547	)
Total comprehensive income		4,363,810		9,572

Condensed financial information of joint ventures

(4) The condensed financial information of joint ventures as of December 31, 2017 and 2016 and for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	Dogus Planet, Inc.			Finnq Co., Ltd.
	As of December 31, 2017
Current assets	￦	39,656			32,232
Cash and cash equivalents		25,818			4,590
Non-current assets		21,159			15,610
Current liabilities		32,622			5,685
Accounts payable, other payables and provision		2,743			2,290
Non-current liabilities		212			13,862
	2017
Revenue		82,791			—
Depreciation and amortization		(6,152	)		(1,077	)
Interest income		781			532
Interest expense		(4	)		(276	)
Loss for the year		(4,535	)		(15,699	)
Total comprehensive loss		(4,535	)		(15,699	)

(In millions of won)
	Dogus Planet, Inc.			PT XL Planet Digital			Finnq Co., Ltd.
	As of December 31, 2016
Current assets	￦	46,433			20,077			48,699
Cash and cash equivalents		45,839			14,985			48,408
Non-current assets		20,218			50,765			673
Current liabilities		26,417			14,513			138
Accounts payable, other payables and provision		1,971			10,306			15
Non-current liabilities		72			1,305			784
	2016
Revenue		53,864			9,492			—
Depreciation and amortization		(5,299	)		(940	)		(12	)
Interest income		394			267			182
Interest expense		(2,139	)		—			—
Income tax benefit		—			51			—
Loss for the year		(22,017	)		(49,438	)		(829	)
Total comprehensive loss		(22,017	)		(49,438	)		(829	)

(In millions of won)
	Dogus Planet, Inc.			PT. Melon Indonesia			PT XL Planet Digital
	2015
Revenue	￦	38,944			17,094			5,536
Depreciation and amortization		(5,318	)		(132	)		(2,746	)
Interest income		465			288			525
Income tax benefit		—			—			7,025
Profit (Loss) for the year		(32,713	)		1,853			(21,381	)
Total comprehensive income (loss)		(32,713	)		1,853			(21,381	)

Reconciliations of financial information of significant associates to carrying amounts of investments in associates in the consolidated financial statements

(5) Reconciliations of financial information of significant associates to carrying amounts of investments in associates in the consolidated financial statements as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Net assets		Ownership interests (%)		Net assets attributable to the ownership interests		Cost-book value differentials		Carrying amount
Associates:
SK hynix Inc.(*1,2)	￦	33,814,467		20.1		6,997,560		1,132,440		8,130,000
KEB HanaCard Co., Ltd.		1,516,162		15.0		227,424		53,564		280,988
SK China Company Ltd.(*1)		1,612,899		27.3		439,857		86,242		526,099

(In millions of won)
	December 31, 2016
	Net assets		Ownership interests (%)		Net assets attributable to the ownership interests		Cost-book value differentials		Carrying amount
Associates:
SK hynix Inc.(*1,2)	￦	24,016,955		20.1		4,970,267		1,161,855		6,132,122
KEB HanaCard Co., Ltd.		1,411,839		15.0		211,776		54,022		265,798

(*1) Net assets of these entities represent net assets excluding those attributable to their non-controlling interests.

(*2) The ownership interest is based on the number of shares owned by the Parent Company as divided by the total shares issued by the investee company. The Group applied the equity method using the effective ownership interest of 20.69% which is based on the number of shares owned by the Parent Company and the total issued shares outstanding less investee’s treasury shares.

Details of the changes in investments in associates and joint ventures accounted for using the equity method

(6) Details of the changes in investments in associates and joint ventures accounted for using the equity method for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)	2017
	Beginning balance		Acquisition and disposition			Share of profit (loss)			Other compre- hensive income (loss)			Impair- ment loss			Other increase (decrease)			Ending balance
Investments in associates
SK China Company Ltd.(*1)	￦	46,354		113,803			2,707			(36,783	)		—			400,018			526,099
Korea IT Fund(*2)		263,850		—			(8,815	)		3,371			—			(1,403	)		257,003
KEB HanaCard Co., Ltd.		265,798		—			15,494			(304	)		—			—			280,988
NanoEnTek, Inc.		39,514		—			(733	)		(63	)		—			—			38,718
SK Industrial Development China Co., Ltd.(*1)		74,717		—			5,154			(1,092	)		—			(78,779	)		—
SK Technology Innovation Company		47,488		—			433			(5,410	)		—			—			42,511
HappyNarae Co., Ltd.		17,236		688			3,929			20			—			—			21,873
SK hynix Inc.(*2)		6,132,122		—			2,175,887			(90,349	)		—			(87,660	)		8,130,000
SK MENA Investment B.V.		15,451		—			131			(1,729	)		—			—			13,853
SKY Property Mgmt. Ltd.(*1)		263,225		—			2,362			1,141			—			(266,728	)		—
S.M. Culture & Contents Co., Ltd.		—		65,341			(375	)		—			—			—			64,966
Xian Tianlong Science and Technology Co., Ltd.		25,880		—			11			—			—			—			25,891
Daehan Kanggun BcN Co., Ltd. and others(*2)		115,181		(1,306	)		(6,924	)		(2,723	)		(1,311	)		(6,438	)		96,479
Sub-total		7,306,816		178,526			2,189,261			(133,921	)		(1,311	)		(40,990	)		9,498,381
Investments in joint ventures
Dogus Planet, Inc.		20,081		2,162			(2,267	)		(5,985	)		—			—			13,991
PT XL Planet Digital(*3)		27,512		(18,864	)		(8,648	)		—			—			—			—
Finnq Co., Ltd		24,174		—			(7,691	)		(9	)		—			—			16,474
Celcom Planet and others		25,740		—			(6,228	)		(833	)		—			(9,087	)		9,592
Sub-total		97,507		(16,702	)		(24,834	)		(6,827	)		—			(9,087	)		40,057
Total	￦	7,404,323		161,824			2,164,427			(140,748	)		(1,311	)		(50,077	)		9,538,438

(*1) Other increase (decrease) is due to merger of SK China Company Ltd., SK Industrial Development China Co., Ltd. and SKY Property Mgmt. Ltd.

(*2) Dividends received from the associates are deducted from the carrying amount during the year ended December 31, 2017.

(*3) During the year ended December 31, 2017, the Group disposed the shares of PT XL Planet Digital and recognized loss on disposal of ￦27,900 million.

(In millions of won)
	2016
	Beginning balance		Acquisition and disposition			Share of profit (loss)			Other compre- hensive income (loss)			Impair- ment loss			Other increase (decrease)			Ending balance
Investments in associates
SK China Company Ltd.	￦	43,814		—			2,257			283			—			—			46,354
Korea IT Fund(*1)		260,456		—			14,864			(5,388	)		—			(6,082	)		263,850
KEB HanaCard Co., Ltd.		254,177		—			11,658			(37	)		—			—			265,798
Candle Media Co., Ltd.		20,144		(18,860	)		(673	)		(611	)		—			—			—
NanoEnTek, Inc.		45,008		—			(3,950	)		(1,544	)		—			—			39,514
SK Industrial Development China Co., Ltd.		86,324		—			(6,298	)		(5,309	)		—			—			74,717
SK Technology Innovation Company		45,891		—			162			1,435			—			—			47,488
HappyNarae Co., Ltd.		17,095		—			240			(99	)		—			—			17,236
SK hynix Inc.(*1)		5,624,493		—			572,086			8,593			—			(73,050	)		6,132,122
SK MENA Investment B.V.		14,929		—			63			459			—			—			15,451
SKY Property Mgmt. Ltd.		251,166		—			16,066			(4,007	)		—			—			263,225
Xian Tianlong Science and Technology Co., Ltd.		25,767		—			113			—			—			—			25,880
Daehan Kanggun BcN Co., Ltd. and others		161,058		(26,798	)		(13,179	)		754			(6,972	)		318			115,181
Sub-total		6,850,322		(45,658	)		593,409			(5,471	)		(6,972	)		(78,814	)		7,306,816
Investments in joint ventures
Dogus Planet, Inc.		15,118		18,722			(11,008	)		(2,751	)		—			—			20,081
PT. Melon Indonesia(*2)		4,339		(3,488	)		918			(1,769	)		—			—			—
PT XL Planet Digital		23,108		29,123			(24,719	)		—			—			—			27,512
Finnq Co., Ltd		—		24,580			(406	)		—			—			—			24,174
Celcom Planet and others		3,406		43,769			(21,435	)		—			—			—			25,740
Sub-total		45,971		112,706			(56,650	)		(4,520	)		—			—			97,507
Total	￦	6,896,293		67,048			536,759			(9,991	)		(6,972	)		(78,814	)		7,404,323

(*1) Dividends received from the associate are deducted from the carrying amount during the year ended December 31, 2016.

(*2) During the year ended December 31, 2016, the Group disposed of all shares of PT. Melon Indonesia and recognized gain on disposal of ￦11,634 million.

Details of cumulative unrecognized equity method losses

(7) The Group discontinued the application of equity method to the following investees due to their carrying amounts being reduced to zero. The details of cumulative unrecognized equity method losses as of December 31, 2017 are as follows:

(In millions of won)
	Unrecognized loss (profit)					Unrecognized change in equity
	Year ended December 31, 2017			Cumulative loss		Year ended December 31, 2017		Cumulative loss
Wave City Development Co., Ltd.	￦	(1,190	)		2,100		—		—
Daehan Kanggun BcN Co., Ltd. and others		(5,475	)		5,316		—		365
	￦	(6,665	)		7,416		—		365

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Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of property and equipment

Property and equipment as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Acquisition cost		Accumulated depreciation			Accumulated impairment loss			Carrying amount
Land	￦	862,861		—			—			862,861
Buildings		1,638,749		(756,099	)		—			882,650
Structures		866,909		(488,334	)		—			378,575
Machinery		30,343,739		(23,262,762	)		(1,179	)		7,079,798
Other		1,722,441		(1,188,893	)		(2,491	)		531,057
Construction in progress		409,941		—			—			409,941
	￦	35,844,640		(25,696,088	)		(3,670	)		10,144,882

(In millions of won)
	December 31, 2016
	Acquisition cost		Accumulated depreciation			Accumulated impairment loss			Carrying amount
Land	￦	835,909		—			—			835,909
Buildings		1,604,863		(704,891	)		—			899,972
Structures		812,010		(453,055	)		—			358,955
Machinery		29,705,088		(22,667,047	)		(1,991	)		7,036,050
Other		1,701,794		(1,138,303	)		(457	)		563,034
Construction in progress		680,292		—			—			680,292
	￦	35,339,956		(24,963,296	)		(2,448	)		10,374,212

Changes in property and equipment

(2) Changes in property and equipment for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017
	Beginning balance		Acquisition		Disposal			Transfer(*)			Depreci- ation			Impair- ment			Business Combination		Other			Ending balance
Land	￦	835,909		13,093		(4,449	)		18,308			—			—			—		—			862,861
Buildings		899,972		5,098		(477	)		29,614			(51,557	)		—			—		—			882,650
Structures		358,955		46,614		(74	)		8,386			(35,306	)		—			—		—			378,575
Machinery		7,036,050		656,731		(41,692	)		1,644,045			(2,214,524	)		(778	)		—		(34	)		7,079,798
Other		563,034		720,431		(9,252	)		(597,404	)		(143,261	)		(2,234	)		315		(572	)		531,057
Construction in progress		680,292		1,317,389		(4,172	)		(1,583,560	)		—			—			—		(8	)		409,941
	￦	10,374,212		2,759,356		(60,116	)		(480,611	)		(2,444,648	)		(3,012	)		315		(614	)		10,144,882

(*) Includes reclassification to intangible assets.

(In millions of won)
	2016
	Beginning balance		Acquisition		Disposal			Transfer(*)			Depreciation			Impairment			Ending balance
Land	￦	812,947		2,464		(3,514	)		24,012			—			—			835,909
Buildings		911,129		4,637		(9,176	)		43,910			(50,528	)		—			899,972
Structures		344,221		33,802		(33	)		15,145			(34,180	)		—			358,955
Machinery		7,342,009		660,629		(45,672	)		1,234,737			(2,152,725	)		(2,928	)		7,036,050
Other		473,438		807,047		(6,052	)		(568,644	)		(142,700	)		(55	)		563,034
Construction in progress		487,512		1,154,424		(9,710	)		(951,934	)		—			—			680,292
	￦	10,371,256		2,663,003		(74,157	)		(202,774	)		(2,380,133	)		(2,983	)		10,374,212

(*) Includes reclassification to intangible assets.

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Investment Property (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Changes in investment properties

(2) Changes in investment properties for the year ended December 31, 2016 are as follows:

(In millions of won)
	2016
	Beginning balance		Reclassification(*)			Depreciation			Ending balance
Land	￦	10,634		(10,634	)		—			—
Buildings		4,437		(4,334	)		(103	)		—
	￦	15,071		(14,968	)		(103	)		—

(*) Includes reclassification to property and equipment.

Income and expenses from investment property

(3) Income and expenses from investment property for the years ended December 31, 2016 and 2015 are as follows:

(In millions of won)
	2016			2015
Rent revenue	￦	386			850
Operating expense		(114	)		(240	)

XML

Goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of goodwill

Goodwill as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Goodwill related to acquisition of Shinsegi Telecom, Inc.	￦	1,306,236		1,306,236
Goodwill related to acquisition of SK Broadband Co., Ltd.		358,443		358,443
Other goodwill		250,338		267,773
	￦	1,915,017		1,932,452

Details of the changes in goodwill

Details of the changes in goodwill for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Beginning balance	￦	1,932,452			1,908,590
Acquisition		35,221			19,974
Impairment loss		(33,441	)		—
Other		(19,215	)		3,888
	￦	1,915,017			1,932,452

XML

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Summary of intangible assets

Intangible assets as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017
	Acquisition cost		Accumulated amortization			Accumulated impairment			Carrying amount
Frequency usage rights	￦	4,843,955		(2,667,015	)		—			2,176,940
Land usage rights		65,841		(50,091	)		—			15,750
Industrial rights		166,082		(54,735	)		—			111,347
Development costs		140,460		(134,828	)		(1,529	)		4,103
Facility usage rights		153,438		(116,987	)		—			36,451
Customer relations		20,796		(16,761	)		—			4,035
Club memberships(*1)		108,382		—			(34,768	)		73,614
Other(*2)		3,911,749		(2,733,485	)		(13,539	)		1,164,725
	￦	9,410,703		(5,773,902	)		(49,836	)		3,586,965

(In millions of won)
	December 31, 2016
	Acquisition cost		Accumulated amortization			Accumulated impairment			Carrying amount
Frequency usage rights	￦	4,843,955		(2,263,127	)		—			2,580,828
Land usage rights		65,148		(44,314	)		—			20,834
Industrial rights		160,897		(39,697	)		—			121,200
Development costs		141,727		(136,446	)		(410	)		4,871
Facility usage rights		151,906		(110,118	)		—			41,788
Customer relations		19,742		(13,090	)		—			6,652
Club memberships(*1)		113,161		—			(39,122	)		74,039
Other(*2)		3,315,921		(2,386,992	)		(2,787	)		926,142
	￦	8,812,457		(4,993,784	)		(42,319	)		3,776,354

(*1) Club memberships are classified as intangible assets with indefinite useful life and are not amortized.

(*2) Other intangible assets primarily consist of computer software and usage rights to a research facility which the Group built and donated, and the Group is given rights-to-use for a definite number of years in turn.

Details of the changes in intangible assets

Research and development expenditures recognized as expense for the years ended December 31, 2017, 2016 and 2015 are as follows:

	2017		2016		2015
Research and development costs expensed as incurred	￦	395,276		344,787		315,790

Intangible assets other than goodwill [Member]

Details of the changes in intangible assets

Details of the changes in intangible assets for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017
	Beginning balance		Acquisition		Disposal			Transfer (*1)			Amortization			Impair- ment (*2)			Business combina- tion(*3)		Others			Ending balance
Frequency usage rights	￦	2,580,828		—		—			—			(403,888	)		—			—		—			2,176,940
Land usage rights		20,834		3,689		(972	)		200			(8,001	)		—			—		—			15,750
Industrial rights		121,200		2,677		(28	)		(5,635	)		(6,870	)		—			4		(1	)		111,347
Development costs		4,871		3,813		(9	)		(793	)		(2,660	)		(1,119	)		—		—			4,103
Facility usage rights		41,788		2,805		(36	)		129			(8,235	)		—			—		—			36,451
Customer relations		6,652		1,054		—			—			(3,671	)		—			—		—			4,035
Club memberships		74,039		5,023		(3,452	)		122			—			(769	)		—		(1,349	)		73,614
Other		926,142		127,396		(19,698	)		503,277			(369,546	)		(16,605	)		14,118		(359	)		1,164,725
	￦	3,776,354		146,457		(24,195	)		497,300			(802,871	)		(18,493	)		14,122		(1,709	)		3,586,965

(*1) Includes reclassification from advance payments and property and equipment.

(*2) The Group recognized the difference between recoverable amount and the carrying amount of club memberships amounting to ￦18,493 million as impairment loss for the year ended December 31, 2017.

(*3) Includes intangible assets acquired as a result of IRIVER LIMITED’s purchase and merge of S.M. LIFE DESIGN COMPANY INC. and SM mobile communications Co., Ltd. during the year ended December 31, 2017.

(In millions of won)
	2016
	Beginning balance		Acquisition		Disposal			Transfer (*2)		Amortiza -tion			Impair- ment(*3)			Business combina- tion		Ending balance
Frequency usage rights(*1)	￦	1,103,517		1,810,076		—			—		(332,765	)		—			—		2,580,828
Land usage rights		26,576		5,338		(1,921	)		—		(9,159	)		—			—		20,834
Industrial rights		116,542		6,226		(148	)		5,004		(6,424	)		—			—		121,200
Development costs		7,472		1,404		—			338		(3,933	)		(410	)		—		4,871
Facility usage rights		48,019		2,181		(50	)		231		(8,593	)		—			—		41,788
Customer relations		7,175		499		—			—		(4,051	)		—			3,029		6,652
Club memberships		91,507		7,983		(7,624	)		—		—			(17,827	)		—		74,039
Other		903,976		141,045		(20,306	)		228,110		(323,397	)		(3,286	)		—		926,142
	￦	2,304,784		1,974,752		(30,049	)		233,683		(688,322	)		(21,523	)		3,029		3,776,354

(*1) During the year ended December 31, 2016, the Parent Company acquired the frequency right for bandwidth blocs in the 2.6 GHz band for ￦1,330,100 million at the spectrum auction held by the Ministry of Science, ICT and Future Planning (MSIP) of Korea and made the initial payment in accordance with the terms of the agreement in August 2016. The remaining consideration will be paid on an annual installment basis for 10 years from August 2016. In addition, the Parent Company extended frequency usage rights for 2.1 GHz band for ￦568,500 million with the initial payment made to MSIP during the year ended December 31, 2016. The remaining consideration will be paid on an annual installment basis for 5 years from December 2016.

(*2) Includes reclassification from advance payments and property and equipment.

(*3) The Group recognized the difference between recoverable amount and the carrying amount of intangible assets, amounting to ￦21,523 million as impairment loss for the year ended December 31, 2016.

Frequency usage rights [member]

Summary of intangible assets

The carrying amount and residual useful lives of frequency usage rights as of December 31, 2017 are as follows, all of which are amortized on a straight-line basis:

(In millions of won)
	Amount		Description	Commencement of amortization		Completion of amortization
800MHz license	￦	141,904	Frequency usage rights relating to CDMA and LTE service		Jul. 2011		Jun. 2021
1.8GHz license		502,480	Frequency usage rights relating to LTE service		Sept. 2013		Dec. 2021
WiBro license		2,957	WiBro service		Mar. 2012		Mar. 2019
2.6GHz license		1,092,770	Frequency usage rights relating to LTE service		Sept. 2016		Dec. 2026
2.1GHz license		436,829	Frequency usage rights relating to W-CDMA and LTE service		Dec. 2016		Dec. 2021
	￦	2,176,940

XML

Borrowings and Debentures (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Short-term borrowings

Short-term borrowings as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	Lender		Annual interest rate (%)		December 31, 2017		December 31, 2016
Short-term borrowings		Shinhan Bank		2.85	￦	30,000		—
		Woori Bank		2.88		—		2,614
Commercial paper		KEB Hana Bank		1.67		50,000		—
Bank overdraft		KEB Hana Bank		3.17		30,000		—
		Shinhan Bank		3.38		20,000		—
					￦	130,000		2,614

Long-term borrowings

Long-term borrowings as of December 31, 2017 and 2016 are as follows:

(In millions of won )
Lender	Annual interest rate (%)		Maturity		December 31, 2017			December 31, 2016
Korea Development Bank(*1)		3.20		Mar. 31, 2020	￦	30,000			—
KEB Hana Bank		3.18		Feb. 28, 2019		40,000			—
Kookmin Bank		1.29		Mar. 15, 2017		—			500
Kookmin Bank		1.95		Mar. 15, 2018		717			3,583
Korea Development Bank(*2)		1.99		Jul. 30, 2019		22,750			35,750
Korea Development Bank(*2)		1.99		Jul. 30, 2019		5,833			9,167
Korea Development Bank(*2)		2.27		Dec. 20, 2021		49,000			49,000
Korea Development Bank(*2)		2.37		Dec. 21, 2022		50,000			—
Export Kreditnamnden(*3)		1.70		Apr. 29, 2022		55,471			76,493
						(USD 51,775	)		(USD 63,296	)
Sub-total						253,771			174,493
Less present value discount						(954	)		(1,586	)
						252,817			172,907
Less current portion						(41,331	)		(33,191	)
					￦	211,486			139,716

(*1) SK Planet Co., Ltd., one of the subsidiaries of the Parent Company entered into a floating-to-fixed interest rate swap agreement to hedge the interest rate risk.

(*2) SK Broadband Co., Ltd., one of the subsidiaries of the Parent Company entered into a floating-to-fixed interest rate swap agreement to hedge the interest rate risk.

(*3) The long-term borrowings are to be repaid by installments on an annual basis from 2014 to 2022.

Debentures

Debentures as of December 31, 2017 and 2016 are as follows:

(In millions of won, thousands of U.S. dollars and thousands of other currencies)
	Purpose	Maturity		Annual interest rate (%)	December 31, 2017		December 31, 2016
Unsecured corporate bonds	Other fund	2018		5.00	￦	200,000		200,000
Unsecured corporate bonds	Operating fund	2021		4.22		190,000		190,000
Unsecured corporate bonds	Operating and refinancing fund	2019		3.24		170,000		170,000
Unsecured corporate bonds		2022		3.30		140,000		140,000
Unsecured corporate bonds		2032		3.45		90,000		90,000
Unsecured corporate bonds	Operating fund	2023		3.03		230,000		230,000
Unsecured corporate bonds		2033		3.22		130,000		130,000
Unsecured corporate bonds		2019		3.30		50,000		50,000
Unsecured corporate bonds		2024		3.64		150,000		150,000
Unsecured corporate bonds(*1)		2029		4.72		60,278		59,600
Unsecured corporate bonds	Refinancing fund	2019		2.53		160,000		160,000
Unsecured corporate bonds		2021		2.66		150,000		150,000
Unsecured corporate bonds		2024		2.82		190,000		190,000
Unsecured corporate bonds	Operating and refinancing fund	2022		2.40		100,000		100,000
Unsecured corporate bonds	refinancing fund	2025		2.49		150,000		150,000
Unsecured corporate bonds		2030		2.61		50,000		50,000
Unsecured corporate bonds	Operating fund	2018		1.89		90,000		90,000
Unsecured corporate bonds		2025		2.66		70,000		70,000
Unsecured corporate bonds		2030		2.82		90,000		90,000
Unsecured corporate bonds	Operating and refinancing fund	2018		2.07		80,000		80,000
Unsecured corporate bonds		2025		2.55		100,000		100,000
Unsecured corporate bonds		2035		2.75		70,000		70,000
Unsecured corporate bonds	Operating fund	2019		1.65		70,000		70,000
Unsecured corporate bonds		2021		1.80		100,000		100,000
Unsecured corporate bonds		2026		2.08		90,000		90,000
Unsecured corporate bonds		2036		2.24		80,000		80,000
Unsecured corporate bonds		2019		1.62		50,000		50,000
Unsecured corporate bonds		2021		1.71		50,000		50,000
Unsecured corporate bonds		2026		1.97		120,000		120,000
Unsecured corporate bonds		2031		2.17		50,000		50,000
Unsecured corporate bonds	Refinancing fund	2020		1.93		60,000		—
Unsecured corporate bonds		2022		2.17		120,000		—
Unsecured corporate bonds		2027		2.55		100,000		—
Unsecured corporate bonds	Operating and refinancing fund	2032		2.65		90,000		—
Unsecured corporate bonds	Operating fund	2020		2.39		100,000		—
Unsecured corporate bonds	Operating and refinancing fund	2022		2.63		80,000		—
Unsecured corporate bonds	Refinancing fund	2027		2.84		100,000		—
Unsecured corporate bonds(*2)	Operating fund	2017		4.28		—		100,000
Unsecured corporate bonds(*2)		2017		3.27		—		120,000
Unsecured corporate bonds(*2)		2019		3.49		210,000		210,000
Unsecured corporate bonds(*2)		2019		2.76		130,000		130,000
Unsecured corporate bonds(*2)		2018		2.23		50,000		50,000
Unsecured corporate bonds(*2)		2020		2.49		160,000		160,000
Unsecured corporate bonds(*2)		2020		2.43		140,000		140,000
Unsecured corporate bonds(*2)		2020		2.18		130,000		130,000
Unsecured corporate bonds(*2)		2019		1.58		50,000		50,000
Unsecured corporate bonds(*2)	Operating and refinancing fund	2021		1.77		120,000		120,000
Unsecured corporate bonds(*2)	Operating fund	2022		2.26		150,000		—
Unsecured corporate bonds(*2)	Refinancing fund		2022			2.34		30,000		—
Unsecured corporate bonds(*2)	Operating and refinancing fund		2022			2.70		140,000		—
Unsecured corporate bonds(*3)	Operating fund		2017			3.48		—		20,000
Convertible bonds(*4)			2019			1.00		5,558		—
Unsecured global bonds			2027			6.63		428,560		483,400
								(USD 400,000	)	(USD 400,000	)
Unsecured private Swiss bonds			2017			1.75		—		354,399
bonds										(CHF 300,000	)
Unsecured global bonds			2018			2.13		749,980		845,950
								(USD 700,000	)	(USD 700,000	)
Unsecured corporate Australian bonds			2017			4.75		—		261,615
										(AUD 300,000	)
Floating rate notes(*5)			2020			3M Libor + 0.88		321,420		362,550
								(USD 300,000)		(USD 300,000	)
Foreign global bonds(*2)			2018			2.88		321,420		362,550
								(USD 300,000	)	(USD 300,000	)
Sub-total								7,107,216		7,220,064
Less discounts on bonds								(21,029	)	(25,858	)
								7,086,187		7,194,206
Less current portion of bonds								(1,489,617	)	(855,276	)
							￦	5,596,570		6,338,930

(*1) The Group eliminated a measurement inconsistency of accounting profit or loss between the bonds and related derivatives by designating the structured bonds as financial liabilities at fair value through profit or loss. The carrying amount of financial liabilities designated at fair value through profit or loss exceeds the principal amount required to pay at maturity by ￦10,278 million as of December 31, 2017.

(*2) Unsecured corporate bonds were issued by SK Broadband Co., Ltd.

(*3) Unsecured corporate bonds were issued by PS&Marketing Corporation.

(*4) During the year ended December 31, 2017, the Parent Company sold the convertible bonds issued by IRIVER LIMITED to third parties.

(*5) As of December 31, 2017, 3M LIBOR rate is 1.69%.

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Long-term Payables - Other (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of Long-term payables - other

(1) Long-term payables — other as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Payables related to acquisition of frequency usage rights	￦	1,328,630		1,602,943
Other(*)		18,133		21,647
	￦	1,346,763		1,624,590

(*) Other includes other long-term employee compensation liabilities.

Summary of Long-term payables - other

(2) As of December 31, 2017 and 2016, details of long-term payables — other which consist of payables related to the acquisition of frequency usage rights are as follows (See Note 16):

(In millions of won)
	December 31, 2017			December 31, 2016
Long-term payables — other	￦	1,710,255			2,013,122
Present value discount on long-term payables — other		(79,874	)		(108,406	)
		1,630,381			1,904,716
Less current portion of long-term payables — other		(301,751	)		(301,773	)
Carrying amount at December 31	￦	1,328,630			1,602,943

Repayment schedule of the principal amount of long-term payables - other related to acquisition of frequency usage rights

(3) The repayment schedule of the principal amount of long-term payables — other related to acquisition of frequency usage rights as of December 31, 2017 is as follows:

(In millions of won)
	Amount
Less than 1 year	￦	302,867
1~3 years		605,734
3~5 years		402,624
More than 5 years		399,030
	￦	1,710,255

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Provisions (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Changes in provisions

(1) Changes in provisions for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	For the year ended December 31, 2017														As of December 31, 2017
	Beginning balance		Increase		Utilization			Reversal			Other		Ending balance		Current		Non-current
Provision for installment of handset subsidy(*1)	￦	24,710		2		(8,898	)		(11,940	)		—		3,874		3,874		—
Provision for restoration(*2)		64,679		12,066		(2,517	)		(1,006	)		45		73,267		40,598		32,669
Emission allowance(*3)		2,788		4,663		(518	)		(2,283	)		—		4,650		4,650		—
Other provisions		5,740		952		(3,757	)		—			—		2,935		2,935		—
	￦	97,917		17,683		(15,690	)		(15,229	)		45		84,726		52,057		32,669

(In millions of won)
	For the year ended December 31, 2016														As of December 31, 2016
	Beginning balance		Increase		Utilization			Reversal			Other		Ending balance		Current		Non-current
Provision for installment of handset subsidy(*1)	￦	5,670		37,530		(18,490	)		—			—		24,710		19,939		4,771
Provision for restoration(*2)		59,954		6,677		(1,082	)		(913	)		43		64,679		37,760		26,919
Emission allowance(*3)		1,477		1,480		(169	)		—			—		2,788		2,788		—
Other provisions		3,104		3,237		(601	)		—			—		5,740		5,740		—
	￦	70,205		48,924		(20,342	)		(913	)		43		97,917		66,227		31,690

(*1) The Group recognizes a provision for handset subsidies given to the subscribers who purchase handsets on an installment basis. The amount recognized as a provision for handset subsidies is the Group’s best estimate of the expenditure required to settle the current obligations to the relevant subscribers at the end of the reporting period, which is calculated as of the present values of estimated handset subsidies to be granted over the relevant service periods, taking into account the customer retention rate for the relevant subscribers. The discount rate used in calculating the present values is based on AAA-rated corporate bonds with a two-year maturity. The customer retention rate is based on the Group’s historical retention rate.

(*2) In the course of the Group’s activities, base station and other assets are installed on leased premises which are expected to have costs associated with restoring the premises to their original conditions where these assets are situated upon ceasing their use on those premises. The associated cash outflows, which are long-term in nature, are generally expected to occur at the dates of the termination of lease contracts to which the assets relate. These restoration costs are calculated on the basis of the identified costs for the current financial year, extrapolated into the future based on management’s best estimates of future trends in prices, inflation, and other factors, and are discounted to present value at a risk-adjusted rate specifically applicable to the liability. Forecasts of estimated future cash outflows are revised in light of future changes in business conditions or technological requirements. The Group records these restoration costs as property and equipment and subsequently expenses them using the straight-line method over the asset’s useful life, and records the accretion of the liability as a charge to finance costs.

(*3) The Group recognizes estimated future payment for the number of emission certificates required to settle the Group’s obligation exceeding the actual number of certificates on hand as emission allowances according to the Act on Allocation and Trading of Greenhouse Gas Emission Permits.

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Lease (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Expected future lease payments and lease revenues

The Group entered into operating lease agreements and sublease agreements in relation to rented office space and the expected future lease payments and lease revenues as of December 31, 2017 are as follows:

(In millions of won)
	Minimum lease payments		Revenues
Less than 1 year	￦	49,289		1,926
1~5 years		101,872		916
	￦	151,161		2,842

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Defined Benefit Liabilities(Assets) (Tables)

12 Months Ended

Dec. 31, 2017

Details of defined benefit liabilities (assets)

(1) Details of defined benefit liabilities(assets) as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017			December 31, 2016
Present value of defined benefit obligations	￦	679,625			595,667
Fair value of plan assets		(663,617	)		(555,175	)
Defined benefit assets(*)		(45,952	)		(30,247	)
Defined benefit liabilities		61,960			70,739

(*) Since the Group entities neither have legally enforceable right nor intention to settle the defined benefit obligations of Group entities with defined benefit assets of other Group entities, defined benefit assets of Group entities have been separately presented from defined benefit liabilities.

Principal actuarial assumptions

(2) Principal actuarial assumptions as of December 31, 2017 and 2016 are as follows:

	December 31, 2017	December 31, 2016
Discount rate for defined benefit obligations	2.58%~4.03%	1.90%~2.96%
Expected rate of salary increase	3.08%~5.93%	2.49%~6.09%

Total amount of expenses recognized in profit and loss

(5) Total amount of expenses recognized in profit and loss (included in labor in the consolidated statement of income) and capitalized into construction-in-progress for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Current service cost	￦	125,526		114,528		106,764
Net interest cost		2,170		3,615		3,257
	￦127,696		118,143		110,021

Details of plan assets

(6) Details of plan assets as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Equity instruments	￦	15,567		13,640
Debt instruments		134,710		95,359
Short-term financial instruments, etc.		513,340		446,176
	￦	663,617		555,175

Effects on defined benefit obligations if each of significant actuarial assumptions changes within expectable and reasonable range

(7) As of December 31, 2017, effects on defined benefit obligations if each of significant actuarial assumptions changes within expectable and reasonable range are as follows:

(In millions of won)
	0.5% Increase			0.5% Decrease
Discount rate	￦	(24,702	)		26,808
Expected salary increase rate		26,988			(25,138	)

Retirement benefit obligation [Member]

Changes in defined benefit liabilities (assets)

(3) Changes in defined benefit obligations for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Beginning balance	￦	595,667			525,269
Current service cost		125,526			114,528
Interest cost		15,991			13,441
Remeasurement - Demographic assumption		(287	)		677
- Financial assumption		(20,731	)		(2,462	)
- Adjustment based on experience		11,561			6,229
Benefit paid		(60,883	)		(55,350	)
Others		12,781			(6,665	)
Ending balance	￦	679,625			595,667

Plan assets [member]

Changes in defined benefit liabilities (assets)

(4) Changes in plan assets for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Beginning balance	￦	555,175			426,413
Interest income		13,821			9,826
Remeasurement		(5,540	)		(6,320	)
Contributions		155,834			159,687
Benefit paid		(60,006	)		(34,247	)
Others		4,333			(184	)
Ending balance	￦	663,617			555,175

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Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Currency and interest rate swap contracts under cash flow hedge accounting

(1) Currency and interest rate swap contracts under cash flow hedge accounting as of December 31, 2017 are as follows:

(In millions of won and thousands of foreign currencies)
Borrowing date	Hedging Instrument(Hedged item)	Hedged risk	Financial institution	Duration of contract
Jul. 20, 2007	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 400,000)	Foreign currency risk	Morgan Stanley and four other banks	Jul. 20, 2007 ~ Jul. 20, 2027
Nov. 1, 2012	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 700,000)	Foreign currency risk	Standard Chartered and eight other banks	Nov. 1, 2012~ May. 1, 2018
Mar. 7, 2013	Floating-to-fixed cross currency interest rate swap (U.S. dollar denominated bonds face value of USD 300,000)	Foreign currency risk and interest rate risk	DBS bank	Mar. 7, 2013 ~ Mar. 7, 2020
Oct. 29, 2013	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 300,000)	Foreign currency risk	Korea Development Bank and others	Oct. 29, 2013 ~ Oct. 26, 2018
Dec. 16, 2013	Fixed-to-fixed cross currency swap (U.S. dollar borrowing amounting to USD 51,775)	Foreign currency risk	Deutsche bank	Dec. 16, 2013 ~ Apr. 29, 2022
Dec. 20, 2016	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 49,000)	Interest rate risk	Korea Development Bank	Dec. 20, 2016~ Dec. 20, 2021
Jan. 30, 2017	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 28,583)	Interest rate risk	Korea Development Bank	Nov. 10, 2016~ Jul. 30, 2019
Mar. 31, 2017	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 30,000)	Interest rate risk	Korea Development Bank	Mar. 31, 2017- Mar. 31, 2020
Dec. 21, 2017	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 50,000)	Interest rate risk	Korea Development Bank	Dec. 5, 2017- Dec. 21, 2022

Details of fair values of the above derivatives recorded in assets or liabilities

(2) As of December 31, 2017, details of fair values of the above derivatives recorded in assets or liabilities are as follows:

(In millions of won and thousands of foreign currencies)
Hedging instrument(Hedged item)	Cash flow hedge			Held for trading		Embedded derivatives		Fair value
Non-current assets:
Redeemable convertible preferred shares issued by Bluehole INC.	￦	—			—		222,257		222,257
Structured bond(face value of KRW 50,000)		—			9,054		—		9,054
Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 400,000)		21,554			—		—		21,554
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 49,000)		307			—		—		307
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 28,583)		43			—		—		43
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 50,000)		(2	)		—		—		(2	)
Total assets								￦	253,213
Current liabilities:
Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 700,000)	￦	(27,791	)		—		—		(27,791	)
Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 300,000)		(615	)		—		—		(615	)
Non-current liabilities:
Floating-to-fixed cross currency interest rate swap (U.S. dollar denominated bonds face value of USD 300,000)		(7,613	)		—		—		(7,613	)
Fixed-to-fixed long-term borrowings (U.S. dollar borrowing amounting to USD 51,775)		(3,106	)		—		—		(3,106	)
Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 30,000)		(345	)		—		—		(345	)
Total liabilities								￦	(39,470	)

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Share Capital and Capital Surplus (Deficit) and Others (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Number of authorized, issued and outstanding common shares and the details of capital surplus and others

The number of authorized, issued and outstanding common shares and the details of capital surplus (deficit) and others as of December 31, 2017 and 2016 are as follows:

(In millions of won, except for share data)
	December 31, 2017			December 31, 2016
Number of authorized shares		220,000,000			220,000,000
Number of issued shares(*1)		80,745,711			80,745,711
Share capital
Common share	￦	44,639			44,639
Capital surplus (deficit) and others:
Paid-in surplus		2,915,887			2,915,887
Treasury shares(Note 24)		(2,260,626	)		(2,260,626	)
Share option(Note 26)		414			—
Others(*2)		(857,912	)		(854,000	)
	￦	(202,237	)		(198,739	)

(*1) In 2002 and 2003, the Parent Company retired treasury shares with reduction of retained earnings before appropriation. As a result, the Parent Company’s outstanding shares have decreased without change in share capital.

(*2) Others primarily consist of the excess of the consideration paid by the Group over the carrying values of net assets acquired from entities under common control.

Details of shares outstanding

There were no changes in share capital during the years ended December 31, 2017 and 2016 and details of shares outstanding as of December 31, 2017 and 2016 are as follows:

(In shares)	2017						2016
	Issued shares		Treasury shares		Outstanding shares		Issued shares		Treasury shares		Outstanding shares
Shares outstanding		80,745,711		10,136,551		70,609,160		80,745,711		10,136,551		70,609,160

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Treasury Shares (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of treasury share

Treasury shares as of December 31, 2017 and 2016 are as follows:

(In millions of won, shares)
	December 31, 2017		December 31, 2016
Number of shares		10,136,551		10,136,551
Acquisition cost	￦	2,260,626		2,260,626

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Hybrid Bonds (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of hybrid bonds

Hybrid bonds classified as equity as of December 31, 2017 are as follows:

(In millions of won)
	Type	Issuance date	Maturity(*1)	Annual interest rate(%)(*2)		Amount
Private hybrid bonds	Unsecured subordinated bearer bond	June 7, 2013	June 7, 2073		4.21	￦	400,000
Issuance costs							(1,482	)
						￦	398,518

Hybrid bonds issued by the Parent Company are classified as equity as there is no contractual obligation for delivery of financial assets to the bond holders. These are subordinated bonds which rank before common shares in the event of a liquidation or reorganization of the Parent Company.

(*1) The Parent Company has a right to extend the maturity under the same terms at issuance without any notice or announcement. The Parent Company also has the right to defer interest payment at its sole discretion.

(*2) Annual interest rate is calculated as yield rate of 5 year national bonds plus premium. According to the step-up clause, additional premium of 0.25% and 0.75%, respectively, after 10 years and 25 years from the issuance date are applied.

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Share option (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of Terms and Conditions Related to Grants of Share Options under Share Option Program

(1) At the shareholders’ meeting held on March 24, 2017, the Parent Company established a share option program that entitles key management personnel the option to purchase common shares of the Parent Company. The terms and conditions related to the grants of the share options under the share option program are as follows:

	Series
	1-1	1-2	1-3
Grant date	March 24, 2017
Types of shares to be issued	66,504 of registered common shares
Grant method	Reissue of treasury shares
Number of shares (in shares)	22,168	22,168	22,168
Exercise price (in won)	246,750	266,490	287,810
Exercise period	Mar. 25, 2019 ~ Mar. 24, 2022	Mar. 25, 2020 ~ Mar. 24, 2023	Mar. 25, 2021 ~ Mar. 24, 2024
Vesting conditions	2 years’ service from the grant date	3 years’ service from the grant date	4 years’ service from the grant date

Summary of Share Compensation Expense Recognized

(2) Share compensation expense recognized during the year ended December 31, 2017 and the remaining share compensation expense to be recognized in subsequent periods are as follows:

(In millions of won)	Share compensation expense
During the year ended December 31, 2017	￦	414
In subsequent periods		977
	￦	1,391

Summary of Inputs Used in Binomial Option Pricing Model

(3) The Group used binomial option pricing model in the measurement of the fair value of the share options at grant date and the inputs used in the model are as follows:

	1-1			1-2			1-3
Risk-free interest rate		1.86	%		1.95	%		2.07	%
Estimated option’s life		5 years			6 years			7 years
Share price (Closing price on the preceding day in won)		262,500			262,500			262,500
Expected volatility		13.38	%		13.38	%		13.38	%
Expected dividends		3.80	%		3.80	%		3.80	%
Exercise price (in won)		246,750			266,490			287,810
Per share fair value of the option (in won)		27,015			20,240			15,480

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Retained Earnings (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of retained earnings

(1) Retained earnings as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Appropriated:
Legal reserve	￦	22,320		22,320
Reserve for research & manpower development		—		60,001
Reserve for business expansion		10,171,138		9,871,138
Reserve for technology development		3,071,300		2,826,300
		13,264,758		12,779,759
Unappropriated		4,571,188		3,173,405
	￦	17,835,946		15,953,164

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Reserves (Tables)

12 Months Ended

Dec. 31, 2017

Details of reserves, net of taxes

(1) Details of reserves, net of taxes, as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017			December 31, 2016
Valuation gain on available-for-sale financial assets	￦	168,211			12,534
Other comprehensive loss of investments in associates		(320,060	)		(179,167	)
Valuation loss on derivatives		(73,828	)		(96,418	)
Foreign currency translation differences for foreign operations		(9,050	)		36,868
	￦	(234,727	)		(226,183	)

Changes in reserves

(2) Changes in reserves for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)	2017
	Valuation gain on available-for-sale financial assets		Other compre- hensive loss of investments in associates			Valuation gain (loss) on derivatives			Foreign currency translation differences for foreign operations			Total
Balance at January 1, 2017	￦	12,534		(179,167	)		(96,418	)		36,868			(226,183	)
Changes, net of taxes		155,677		(140,893	)		22,590			(45,918	)		(8,544	)
Balance at December 31, 2017	￦	168,211		(320,060	)		(73,828	)		(9,050	)		(234,727	)

(In millions of won)
	2016
	Valuation gain (loss) on available-for-sale financial assets			Other compre- hensive loss of investments in associates			Valuation loss on derivatives			Foreign currency translation differences for foreign operations		Total
Balance at January 1, 2016	￦	232,316			(169,520	)		(83,200	)		29,707		9,303
Changes, net of taxes		(219,782	)		(9,647	)		(13,218	)		7,161		(235,486	)
Balance at December 31, 2016	￦	12,534			(179,167	)		(96,418	)		36,868		(226,183	)

Valuation gain (loss) on available-for-sale financial assets [Member]

Changes in reserves

(3) Changes in valuation gain on available-for-sale financial assets for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017		2016
Balance at January 1	￦	12,534		232,316
Amount recognized as other comprehensive income during the year, net of taxes		132,586		4,606
Amount reclassified through profit or loss, net of taxes 23,091		23,091		(224,388	)
Balance at December 31	￦	168,211		12,534

Valuation gain (loss) on derivatives [Member]

Changes in reserves

(4) Changes in valuation gain (loss) on derivatives for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017			2016
Balance at January 1	￦	(96,418	)		(83,200	)
Amount recognized as other comprehensive loss during the year, net of taxes		17,965			(12,213	)
Amount reclassified through profit or loss, net of taxes		4,625			(1,005	)
Balance at December 31	￦	(73,828	)		(96,418	)

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Other Operating Income and Expenses (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Details of other operating income and expenses

Details of other operating income andexpenses for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Other Operating Income:
Gain on disposal of property and equipment and intangible assets		13,991		6,908		7,140
Others(*)		18,006		59,640		23,795
	￦	31,997		66,548		30,935
Other Operating Expenses:
Communication	￦	27,973		31,196		43,979
Utilities		299,825		277,497		270,621
Taxes and dues		27,819		35,020		36,118
Repair		333,101		326,076		312,517
Research and development		395,276		344,787		315,790
Training		32,853		33,303		37,278
Bad debt for accounts receivable — trade		34,584		37,820		60,450
Travel		24,095		25,263		27,860
Supplies and other		111,170		113,930		176,248
Loss on disposal of property and equipment and intangible assets		60,086		63,797		21,392
Impairment loss on other investment securities		9,003		24,033		42,966
Impairment loss on property and equipment and intangible assets		54,946		24,506		35,845
Donations		112,634		96,633		72,454
Bad debt for accounts receivable — other		5,793		40,312		15,323
Others(*)		101,589		49,593		55,536
	￦	1,630,747		1,523,766		1,524,377

(*) See Note 5-(2).

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Finance Income and Costs (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Details of finance income and costs

(1) Details of finance income and costs for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Finance Income:
Interest income	￦	76,045		54,353		45,884
Gain on sale of accounts receivable — trade		18,548		18,638		—
Dividends		12,416		19,161		16,102
Gain on foreign currency transactions		13,676		14,186		18,923
Gain on foreign currency translations		7,110		5,085		5,090
Gain on disposal of long-term investment securities		4,890		459,349		10,786
Gain on valuation of derivatives		223,943		4,132		1,927
Reversal of impairment loss on available-for-sale financial assets		9,900		—		—
Gain relating to financial assets at fair value through profit or loss		33		25		—
Gain relating to financial liability at fair value through profit or loss		—		121		5,188
	￦	366,561		575,050		103,900
Finance Costs:
Interest expense	￦	299,100		290,454		297,662
Loss on sale of accounts receivable — trade		9,682		—		—
Loss on foreign currency transactions		19,263		16,765		17,931
Loss on foreign currency translations		8,419		3,991		4,750
Loss on disposal of long-term investment securities		36,024		2,919		2,599
Loss on settlement of derivatives		10,031		3,428		4,845
Loss relating to financial liability at fair value through profit or loss		678		4,018		526
Impairment loss on long-term investment securities(*)		14,519		5,255		21,787
Other finance costs		35,900		—		—
	￦	433,616		326,830		350,100

(*) See Note 30-(5).

Details of interest income included in finance income

(2) Details of interest income included in finance income for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Interest income on cash equivalents and short-term financial instruments	￦	28,130		20,203		20,009
Interest income on installment receivables and others		47,915		34,150		25,875
	￦	76,045		54,353		45,884

Details of interest expenses included in finance costs

(3) Details of interest expenses included in finance costs for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Interest expense on borrowings	￦	11,774		7,962		19,577
Interest expense on debentures		228,568		239,560		238,450
Interest on finance lease liabilities		—		—		58
Others		58,758		42,932		39,577
	￦	299,100		290,454		297,662

Finance income and costs by category of financial instruments

(4) Finance income and costs by category of financial instruments for the years ended December 31, 2017, 2016 and 2015 are as follows. Bad debt expense (reversal of allowance for doubtful accounts) for accounts receivable — trade, loans and receivables are presented and explained separately in Note 7.

(i)    Finance income

(In millions of won)
	2017		2016		2015
Financial Assets:
Financial assets at fair value through profit or loss	￦	223,976		4,157		1,927
Available-for-sale financial assets		30,598		484,300		31,220
Loans and receivables		111,677		86,256		64,749
Sub-total		366,251		574,713		97,896
Financial Liabilities:
Financial liabilities at fair value through profit or loss		—		121		5,188
Financial liabilities measured at amortized cost		310		216		816
Sub-total		310		337		6,004
	￦	366,561		575,050		103,900

(ii)    Finance costs

(In millions of won)
	2017		2016		2015
Financial Assets:
Financial assets at fair value through profit or loss	￦	—		2,791		4,188
Available-for-sale financial assets		86,445		8,174		24,386
Loans and receivables		37,040		15,810		15,861
Derivatives designated as hedging instruments		—		637		657
Sub-total		123,485		27,412		45,092
Financial Liabilities:
Financial liabilities at fair value through profit or loss		678		4,018		526
Financial liabilities measured at amortized cost		299,422		295,400		304,482
Derivatives designated as hedging instruments		10,031		—		—
Sub-total		310,131		299,418		305,008
	￦	433,616		326,830		350,100

(iii)    Other comprehensive income (loss)

(In millions of won)
	2017		2016			2015
Financial Assets:
Available-for-sale financial assets	￦	158,440		(223,981	)		(3,661	)
Derivatives designated as hedging instruments		1,554		(172	)		(3,248	)
Sub-total		159,994		(224,153	)		(6,909	)
Financial Liabilities:
Derivatives designated as hedging instruments		21,032		(13,046	)		1,977
Sub-total		21,032		(13,046	)		1,977
	￦	181,026		(237,199	)		(4,932	)

Details of impairment losses for financial assets

(5) Details of impairment losses for financial assets for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Available-for-sale financial assets(*)	￦	14,519		5,255		21,787
Accounts receivable — trade		34,584		37,820		60,450
Other receivables		5,793		40,312		15,323
	￦	54,896		83,387		97,560

(*) This is included in other finance costs (See Note 30-(1)).

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Income Tax Expense (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of income tax expenses

(1) Income tax expenses for the years ended December 31, 2017, 2016 and 2015 consist of the following:

(In millions of won)
	2017			2016			2015
Current tax expense
Current year	￦	424,773			473,543			417,022
Current tax of prior years(*)		(105,158	)		(11,925	)		(4,124	)
		319,615			461,618			412,898
Deferred tax expense
Changes in net deferred tax assets		426,039			(25,580	)		106,399
Others (tax rate differences, etc.)		—			—			183
Income tax expense	￦	745,654			436,038			519,480

(*) Current tax of prior years are mainly composed of the income tax refund due to a change in the interpretation of the tax authority in relation to the income tax previously recognized by the Group.

Difference between income taxes computed using the statutory corporate income tax rates and the recorded income taxes

(2) The difference between income taxes computed using the statutory corporate income tax rates and the recorded income taxes for the years ended December 31, 2017, 2016 and 2015 is attributable to the following:

(In millions of won)
	2017			2016			2015
Income taxes at statutory income tax rate	￦	823,124			506,804			492,096
Non-taxable income		(40,080	)		(38,989	)		(85,589	)
Non-deductible expenses		31,285			52,648			44,770
Tax credit and tax reduction		(34,300	)		(29,484	)		(25,756	)
Changes in unrecognized deferred taxes		31,857			(84,276	)		83,623
Others (income tax refund, etc.)(*)		(66,232	)		29,335			10,336
Income tax expense	￦	745,654			436,038			519,480

(*) Based on the amendment to Korean Tax Law that was enacted in 2017, the income tax rate for taxable income in excess of ￦300,000 million is changed from 24.2% to 27.5%, which will be effective from January 1, 2018. The Group remeasured deferred tax assets and liabilities as a result of this rate change.

Deferred taxes directly charged to (credited from) equity

(3) Deferred taxes directly charged to (credited from) equity for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017			2016		2015
Valuation gain (loss) on available-for-sale financial assets	￦	(55,883	)		82,993		2,461
Share of other comprehensive income (loss) of associates		(260	)		2		(63	)
Valuation gain (loss) on derivatives		(3,019	)		4,454		(448	)
Remeasurement of defined benefit liabilities		1,618			3,174		2,719
	￦	(57,544	)		90,623		4,669

Details of the changes in deferred tax assets (liabilities)

(4) Details of the changes in deferred tax assets (liabilities) for the years ended December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017
	Beginning			Deferred tax expense (income)			Directly charged to (credited from) equity			Others			Ending
Deferred tax assets (liabilities) related to temporary differences:
Allowance for doubtful accounts	￦	61,911			5,091			—			—			67,002
Accrued interest income		(616	)		(1,851	)		—			—			(2,467	)
Available-for-sale financial assets		101,472			8,192			(55,883	)		—			53,781
Investments in subsidiaries, associates and joint ventures		(476,098	)		(461,271	)		(260	)		—			(937,629	)
Property and equipment (depreciation)		(253,323	)		17,980			—			—			(235,343	)
Provisions		7,448			(5,136	)		—			—			2,312
Retirement benefit obligation		35,505			1,237			1,618			—			38,360
Valuation gain on derivatives		28,975			—			(3,019	)		—			25,956
Gain or loss on foreign currency translation		19,369			2,562			—			—			21,931
Reserve for research and manpower development		(4,775	)		2,388			—			—			(2,387	)
Goodwill		3,105			(938	)		—			—			2,167
Others		34,911			(29,248	)		—			(2,324	)		3,339
		(442,116	)		(460,994	)		(57,544	)		(2,324	)		(962,978	)
Deferred tax assets related to unused tax loss carryforwards and tax credit carryforwards
Tax loss carryforwards		37,462			34,955			—			—			72,417
	￦	(404,654	)		(426,039	)		(57,544	)		(2,324	)		(890,561	)

(In millions of won)
	2016
	Beginning			Deferred tax expense (income)			Directly charged to (credited from) equity		Ending
Deferred tax assets (liabilities) related to temporary differences:
Allowance for doubtful accounts	￦	59,957			1,954			—		61,911
Accrued interest income		(2,567	)		1,951			—		(616	)
Available-for-sale financial assets		30,365			(11,886	)		82,993		101,472
Investments in subsidiaries, associates and joint ventures		(355,273	)		(120,827	)		2		(476,098	)
Property and equipment (depreciation)		(327,572	)		74,249			—		(253,323	)
Provisions		2,485			4,963			—		7,448
Retirement benefit obligation		28,327			4,004			3,174		35,505
Valuation gain on derivatives		24,521			—			4,454		28,975
Gain or loss on foreign currency translation		19,517			(148	)		—		19,369
Reserve for research and manpower development		(7,162	)		2,387			—		(4,775	)
Goodwill		3,713			(608	)		—		3,105
Unearned revenue (activation fees)		2,065			(2,065	)		—		—
Others		(23,782	)		58,693			—		34,911
		(545,406	)		12,667			90,623		(442,116	)
Deferred tax assets related to unused tax loss carryforwards and tax credit carryforwards
Tax loss carryforwards		24,549			12,913			—		37,462
	￦	(520,857	)		25,580			90,623		(404,654	)

Details of temporary differences, unused tax loss carryforwards and unused tax credits carryforwards which are not recognized as deferred tax assets

(5) Details of temporary differences, unused tax loss carryforwards and unused tax credits carryforwards which are not recognized as deferred tax assets, in the consolidated statements of financial position as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017		December 31, 2016
Allowance for doubtful accounts	￦	88,521		165,935
Investments in subsidiaries, associates and joint ventures		168,268		228,025
Other temporary differences		425,653		320,260
Unused tax loss carryforwards		921,309		755,050
Unused tax credit carryforwards		4,092		1,211

Unused tax loss carryforwards and unused tax credit carryforwards which are not recognized as deferred tax assets

(6) The amount of unused tax loss carryforwards and unused tax credit carryforwards which are not recognized as deferred tax assets as of December 31, 2017 are expiring within:

(In millions of won)
	Unused tax loss carryforwards		Unused tax credit carryforwards
Less than 1 year	￦	—		869
1 ~ 2 years		7,686		101
2 ~ 3 years		358,237		119
More than 3 years		555,386		3,003
	￦	921,309		4,092

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Earnings per Share (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of basic earnings per share

1) Basic earnings per share for the years ended December 31, 2017, 2016 and 2015 are calculated as follows:

(In millions of won, shares)
	2017			2016			2015
Basic earnings per share attributable to owners of the Parent Company:
Profit attributable to owners of the Parent Company	￦	2,599,829			1,675,967			1,518,604
Interest on hybrid bonds		(16,840	)		(16,840	)		(16,840	)
Profit attributable to owners of the Parent Company on common shares		2,582,989			1,659,127			1,501,764
Weighted average number of common shares outstanding		70,609,160			70,609,160			71,551,966
Basic earnings per share (in won)	￦	36,582			23,497			20,988

Weighted average number of common shares outstanding

2) The weighted average number of common shares outstanding for the years ended December 31, 2017, 2016 and 2015 are calculated as follows:

(In shares)
	2017			2016			2015
Issued common shares at January 1		80,745,711			80,745,711			80,745,711
Effect of treasury shares		(10,136,551	)		(10,136,551	)		(9,193,745	)
Weighted average number of common shares outstanding at December 31		70,609,160			70,609,160			71,551,966

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Dividends (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Details of dividend declared

Details of dividend declared for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won, except for face value and share data)
Year	Dividend type	Number of shares outstanding		Face value (in won)		Dividend ratio			Dividends
2017	Cash dividends (Interim)		70,609,160		500		200	%	￦	70,609
	Cash dividends (Year-end)		70,609,160		500		1,800	%		635,482
									￦	706,091
2016	Cash dividends (Interim)		70,609,160		500		200	%	￦	70,609
	Cash dividends (Year-end)		70,609,160		500		1,800	%		635,482
									￦	706,091
2015	Cash dividends (Interim)		72,629,160		500		200	%	￦	72,629
	Cash dividends (Year-end)		70,609,160		500		1,800	%		635,482
									￦	708,111

Dividends yield ratios

(2)    Dividends yield ratio

Dividends yield ratios for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In won)
Year	Dividend type	Dividend per share	Closing price at year-end	Dividend yield ratio
2017	Cash dividends	10,000	267,000	3.75%
2016	Cash dividends	10,000	224,000	4.46%
2015	Cash dividends	10,000	215,500	4.64%

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Financial Risk Management (Tables)

12 Months Ended

Dec. 31, 2017

Maximum credit exposure

The maximum credit exposure as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	2017		2016
Cash and cash equivalents	￦	1,457,416		1,505,082
Financial instruments		618,002		469,705
Available-for-sale financial assets		19,928		6,755
Accounts receivable — trade		2,138,755		2,261,311
Loans and other receivables		1,962,083		1,701,249
Derivative financial assets		30,956		214,770
	￦	6,227,140		6,158,872

Contractual maturities of financial liabilities

Contractual maturities of financial liabilities as of December 31, 2017 are as follows:

(In millions of won)
	Carrying amount		Contractual cash flows		Less than 1 year		1 - 5 years		More than 5 years
Accounts payable — trade	￦	351,711		351,711		351,711		—		—
Borrowings(*1)		382,817		397,776		177,910		219,866		—
Debentures(*1)		7,086,187		8,230,952		1,682,206		3,675,178		2,873,568
Accounts payable — other and others(*2)		4,865,519		5,030,105		3,519,489		1,093,611		417,005
	￦	12,686,234		14,010,544		5,731,316		4,988,655		3,290,573

The Group does not expect that the cash flows included in the maturity analysis could occur significantly earlier or at different amounts.

(*1) Includes interest payables.

(*2) The Group provides with USD 12,240,000 of payment guarantees for Celcom Planet, one of the joint ventures of the Group, in relation to its borrowings. The contractual cash flows for accounts payable — other and others include the maximum amount that the Group is required to pay in connection with the guarantees.

Periods in which cash flows from cash flow hedge derivatives are expected to occur

As of December 31, 2017, periods in which cash flows from cash flow hedge derivatives are expected to occur are as follows:

(In millions of won)
	Carrying amount			Contractual cash flows			Less than 1 year			1 - 5 years			More than 5 years
Assets	￦	21,902			17,118			7,446			28,075			(18,403	)
Liabilities		(39,470	)		(40,220	)		(28,960	)		(11,260	)		—
	￦	(17,568)			(23,102)			(21,514	)		16,815			(18,403	)

Debt-equity ratio

Debt-equity ratio as of December 31, 2017 and 2016 are as follows:

(In millions of won)
	December 31, 2017			December 31, 2016
Total liabilities	￦	15,399,474			15,181,233
Total equity		18,029,195			16,116,430
Debt-equity ratios		85.41	%		94.20	%

Fair value and carrying amount of financial assets and liabilities including fair value hierarchy

Fair value and carrying amount of financial assets and liabilities including fair value hierarchy as of December 31, 2017 are as follows:

(In millions of won)
	December 31, 2017
	Carrying amount		Level 1		Level 2		Level 3		Total
Financial assets that are measured at fair value
Financial assets at fair value through profit or loss	￦	328,314		—		106,057		222,257		328,314
Derivative financial assets		21,902		—		21,902		—		21,902
Available-for-sale financial assets		734,487		589,202		47,383		97,902		734,487
	￦	1,084,703		589,202		175,342		320,159		1,084,703
Financial liabilities that are measured at fair value
Financial liabilities at fair value through profit or loss	￦	60,278		—		60,278		—		60,278
Derivative financial liabilities		39,470		—		39,470		—		39,470
	￦	99,748		—		99,748		—		99,748
Financial liabilities that are not measured at fair value
Borrowings	￦	382,817		—		383,748		—		383,748
Debentures		7,025,909		—		7,325,370		—		7,325,370
Long-term payables — other		1,649,466		—		1,766,451		—		1,766,451
	￦	9,058,192		—		9,475,569		—		9,475,569

2) Fair value and carrying amount of financial assets and liabilities including fair value hierarchy as of December 31, 2016 are as follows:

(In millions of won)
	December 31, 2016
	Carrying amount		Level 1		Level 2		Level 3		Total
Financial assets that are measured at fair value:
Financial assets at fair value through profit or loss	￦	7,368		—		7,368		—		7,368
Derivative financial assets		207,402		—		207,402		—		207,402
Available-for-sale financial assets		741,285		526,363		107,364		107,558		741,285
	￦	956,055		526,363		322,134		107,558		956,055
Financial liabilities that are measured at fair value:
Financial liabilities at fair value through profit or loss	￦	59,600		—		59,600		—		59,600
Derivative financial liabilities		87,153		—		87,153		—		87,153
	￦	146,753		—		146,753		—		146,753
Financial liabilities that are not measured at fair value:
Borrowings	￦	175,521		—		177,600		—		177,600
Debentures		7,134,606		—		7,568,361		—		7,568,361
Long-term payables — other		1,926,363		—		2,103,788		—		2,103,788
	￦	9,236,490		—		9,849,749		—		9,849,749

Interest rates used by the group for the fair value measurement

Interest rates used by the Group for the fair value measurement as of December 31, 2017 are as follows:

	Interest rate
Derivative instruments		1.54% ~ 2.67%
Borrowings and debentures		2.48% ~ 2.55%
Long-term payables — other		2.23% ~ 2.60%

Carrying amount of financial instruments recognized of which offset agreements are applicable

Carrying amount of financial instruments recognized of which offset agreements are applicable as of December 31, 2017 and 2016 are as follows:

(In millions of won)	2017
	Gross financial instruments recognized		Amount offset			Net financial instruments presented on the statements of financial position		Relevant amount not offset on the statements of financial position			Net amount
								Financial instruments
Financial assets:
Derivatives(*)	￦	26,645		—			26,645		(19,875	)		6,770
Accounts receivable — trade and others		93,146		(92,409	)		737		—			737
	￦	119,791		(92,409	)		27,382		(19,875	)		7,507
Financial liabilities:
Derivatives(*)	￦	19,875		—			19,875		(19,875	)		—
Accounts payable — other and others		92,409		(92,409	)		—		—			—
	￦	112,284		(92,409	)		19,875		(19,875	)		—

(In millions of won)	2016
	Gross financial instruments recognized		Amount offset			Net financial instruments presented on the statements of financial position		Relevant amount not offset on the statements of financial position			Net amount
								Financial instruments
Financial assets:
Derivatives(*)	￦	87,566		—			87,566		(87,153	)		413
Accounts receivable — trade and others		114,135		(103,852	)		10,283		—			10,283
	￦	201,701		(103,852	)		97,849		(87,153	)		10,696
Financial liabilities:
Derivatives(*)	￦	87,153		—			87,153		(87,153	)		—
Accounts payable — other and others		103,852		(103,852	)		—		—			—
	￦	191,005		(103,852	)		87,153		(87,153	)		—

(*) The Group entered into derivative contracts which include enforceable master netting arrangement in accordance with International Swap and Derivatives Association (ISDA). Generally, all contracts made with the identical currencies are settled from one party to another by combining one net amount. In this case, all contracts are liquidated and paid off at net amount by evaluating liquidation value if credit events such as bankruptcy occur.

Currency risk [member]

Monetary assets and liabilities denominated in foreign currencies

Monetary assets and liabilities denominated in foreign currencies as of December 31, 2017 are as follows:

(In millions of won, thousands of foreign currencies)
	Assets				Liabilities
	Foreign currencies		Won equivalent		Foreign currencies		Won equivalent
USD		124,901	￦	133,836		1,817,808	￦	1,947,599
EUR		15,669		20,044		63		80
JPY		596,059		5,658		169,729		1,611
Others		—		530		—		195
			￦	160,068			￦	1,949,485

Impact on income before income tax of a hypothetical change in exchange rates

As of December 31, 2017, a hypothetical change in exchange rates by 10% would have increase (reduce) the Group’s income before income tax as follows:

(In millions of won)
	If increased by 10%		If decreased by 10%
USD	￦	5,590		(5,590	)
EUR		1,997		(1,997	)
JPY		405		(405	)
Others		34		(34	)
	￦	8,026		(8,026	)

Available- for-sale financial assets [Member] | Level 3 [member]

Fair value of assets

There have been no transfers from Level 2 to Level 1 in 2017 and changes of financial assets classified as Level 3 for the year ended December 31, 2017 are as follows:

(In millions of won)
	Balance at beginning		Valuation		Transfer		Other compre- hensive loss			Disposal			Balance at ending
Financial assets at fair value through profit or loss(*)	￦	—		222,257		—		—			—			222,257
Available-for-sale financial assets		107,558		—		3,938		(8,942	)		(4,652	)		97,902

(*) The Group holds redeemable convertible preferred shares issued by Bluehole INC. The conversion rights attached to the investments are bifurcated from the host contract as embedded derivatives and the Group recognized ￦222,257 million as financial assets at FVTPL and gain on valuation of derivatives, respectively, as of and during the year ended December 31, 2017. The host contract was recognized as available-for-sale financial assets of ￦15,342 million measured by discounting the amount of collection at maturity including the principal, guaranteed interests, and dividend. The fair value of the conversion rights were measured using the binomial option pricing model by considering inputs such as expected volatility, exercise price, and common share price.

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Related Parties and Others (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Compensation for the key management

The compensation given to such key management for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Salaries	￦	2,169		1,645		1,971
Defined benefits plan expenses		258		424		626
Share option		414		—		—
	￦	2,841		2,069		2,597

Transactions with related parties

Transactions with related parties for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
		2017
Scope	Company	Operating revenue and others		Operating expense and others		Acquisition of property and equipment		Collection of loans
Ultimate Controlling Entity	SK Holdings Co., Ltd.(*1)	￦	25,049		600,600		283,556		—
Associates	F&U Credit information Co., Ltd.		3,431		52,150		153		—
	HappyNarae Co., Ltd.		3,025		29,276		68,472		—
	SK hynix Inc(*2)		123,873		251		—		—
	KEB HanaCard Co., Ltd.		17,873		15,045		—		—
	Others(*3)		10,720		33,389		940		204
			158,922		130,111		69,565		204
Others	SK Engineering & Construction Co., Ltd.		5,865		1,077		—		—
	SK Networks Co., Ltd.		21,694		1,220,251		671		—
	SK Networks Services Co., Ltd.		510		96,949		6,346		—
	SK Telesys Co., Ltd.		417		51,394		152,659		—
	SK TNS Co., Ltd.		137		37,051		494,621		—
	SK Energy Co., Ltd.		8,505		779		—		—
	SK Gas Co., Ltd.		2,727		4		—		—
	SK Innovation Co., Ltd.		7,639		950		—		—
	SK Shipping Co., Ltd.		3,183		35		—		—
	Ko-one energy service Co., Ltd		5,164		44		—		—
	SK infosec Co., Ltd.		1,185		52,634		15,648		—
	SKC INFRA SERVICE Co., Ltd.		19		46,900		47,163		—
	Others		18,233		28,209		17		—
			75,278		1,536,277		717,125		—
Total		￦	259,249		2,266,988		1,070,246		204

(*1) Operating expense and others include ￦203,635 million of dividends paid by the Parent Company.

(*2) Operating revenue and others include ￦87,660 million of dividends received from SK Hynix Inc. which was deducted from the investment in associates.

(*3) Operating revenue and others include ￦6,597 million of dividends received from the Korea IT Fund and others.

(In millions of won)		2016
Scope	Company	Operating revenue and others		Operating expense and others		Acquisition of property and equipment		Loans		Collection of loans
Ultimate Controlling Entity	SK Holdings Co., Ltd.(*1)	￦	23,104		652,855		235,502		—		—
Associates	F&U Credit information Co., Ltd.		2,865		47,905		—		—		—
	HappyNarae Co., Ltd.		304		15,506		38,984		—		—
	SK hynix Inc.(*2)		100,861		306		—		—		—
	KEB HanaCard Co., Ltd.		19,730		14,804		—		—		—
	Others(*3)		8,018		21,853		1,573		1,100		3,194
			131,778		100,374		40,557		1,100		3,194
Others	SK Engineering & Construction Co., Ltd.		5,916		1,739		10,694		—		—
	SK Networks Co., Ltd.		13,756		1,131,567		—		—		—
	SK Networks Services Co., Ltd.		1,248		94,906		6,793		—		—
	SK Telesys Co., Ltd.		419		52,488		142,605		—		—
	SK TNS Co., Ltd.		109		48,192		387,496		—		—
	SK Energy Co., Ltd.		7,670		834		—		—		—
	SK Gas Co., Ltd.		2,500		4		—		—		—
	SK Innovation Co., Ltd.		9,757		915		1,080		—		—
	SK Shipping Co., Ltd.		5,435		—		—		—		—
	Ko-one energy service Co., Ltd		6,005		46		—		—		—
	SK infosec Co., Ltd.		230		53,068		19,882		—		—
	SKC INFRA SERVICE Co., Ltd.		43		30,663		32,141		—		—
	Others		13,437		17,626		246		—		—
			66,525		1,432,048		600,937		—		—
Total		￦	221,407		2,185,277		876,996		1,100		3,194

(*1) Operating expense and others include ￦203,635 million of dividends paid by the Parent Company.

(*2) Operating revenue and others include ￦73,050 million of dividends paid by the associate which was deducted from the investment in associates.

(*3) Operating revenue and others include ￦6,082 million of dividends received from the Korea IT Fund.

(In millions of won)
		2015
Scope	Company	Operating revenue and others		Operating expense and others		Acquisition of property and equipment		Loans		Collection of loans
Ultimate Controlling Entity	SK Holdings Co., Ltd. (formerly, SK C&C Co., Ltd.)(*1)	￦	20,260		324,078		236,414		—		—
	SK Holdings Co., Ltd. (formerly, SK Holdings Co., Ltd.)(*2,3)		1,299		212,378		117		—		—
			21,559		536,456		236,531		—		—
Associates	F&U Credit information Co., Ltd.		2,510		43,967		—		—		—
	HappyNarae Co., Ltd.		297		6,886		13,495		—		—
	SK hynix Inc.(*4)		55,949		2,384		—		—		—
	SK Wyverns Baseball Club., Ltd.		3,849		18,544		—		—		204
	KEB HanaCard Co., Ltd.		21,414		16,057		—		—		—
	Xian Tianlong Science and Technology Co., Ltd.		—		—		—		8,287		—
	Others(*5)		6,397		11,917		1,864		690		—
			90,416		99,755		15,359		8,977		204
Other	SK Engineering & Construction Co., Ltd.		15,598		27,243		240,701		—		—
	SK Networks Co., Ltd.		11,923		1,257,975		2		—		—
	SK Networks Services Co., Ltd.		10,491		94,097		6,472		—		—
	SK Telesys Co., Ltd.		397		48,900		141,870		—		—
	SK Energy Co., Ltd.		9,930		978		—		—		—
	SK Gas Co., Ltd.		3,561		2		—		—		—
	Others		29,409		71,314		194,945		—		—
			81,309		1,500,509		583,990		—		—
Total		￦	193,284		2,136,720		835,880		8,977		204

(*1) On August 1, 2015, SK C&C Co., Ltd., the ultimate controlling entity of the Parent Company merged with SK Holdings Co., Ltd., its equity method investee, and changed its name to SK Holdings Co., Ltd.

(*2) These relates to transactions occurred before July 31, 2015, the date of merger with SK C&C Co., Ltd.

(*3) Operating expense and others include ￦191,416 million of dividends paid by the Parent Company.

(*4) Operating revenue and others include ￦43,830 million of dividends paid by SK hynix Inc. and was deducted from the investment in associates.

(*5) Operating revenue and others include ￦2,103 million and ￦457 million of dividends paid by Korea IT Fund and UniSK, respectively, and was deducted from the investments in associates.

Account balances with related parties

(4) Account balances with related parties as of December 31, 2017 and 2016 are as follows:

(In millions of won)
		December 31, 2017
		Accounts receivable				Accounts payable
Scope	Company	Loans		Accounts receivable-trade and others		Accounts payable-other and others
Ultimate Controlling Entity	SK Holdings Co., Ltd.	￦	—		2,068		148,066
Associates	HappyNarae Co., Ltd.		—		15		6,865
	F&U Credit information Co., Ltd.		—		21		1,612
	SK hynix Inc.		—		2,803		94
	Wave City Development Co., Ltd.		—		38,412		—
	Daehan Kanggun BcN Co., Ltd.(*)		22,147		—		—
	KEB HanaCard Co., Ltd.		—		1,427		11,099
	S.M. Culture & Contents Co., Ltd.		—		448		8,963
	Xian Tianlong Science and Technology Co., Ltd.		7,032		—		—
	Others		611		2,272		1,164
			29,790		45,398		29,797
Other	SK Engineering & Construction Co., Ltd.		—		2,033		69
	SK Networks. Co., Ltd.		—		3,050		267,297
	SK Networks Services Co., Ltd.		—		15		9,522
	SK Telesys Co., Ltd.		—		36		58,346
	SK TNS Co., Ltd.		—		3		140,311
	SK Innovation Co., Ltd.		—		4,112		599
	SK Energy Co., Ltd.		—		2,965		582
	SK Gas Co., Ltd.		—		1,941		9
	Others		—		2,998		27,318
			—		17,153		504,053
Total		￦	29,790		64,619		681,916

(*) The Parent Company has recognized allowances for doubtful accounts on the entire balance of loans to Daehan Kanggun BcN Co., Ltd as of December 31, 2017.

(In millions of won)
		December 31, 2016
		Accounts receivable				Accounts payable
Scope	Company	Loans		Accounts receivable-trade and others		Accounts payable-other and others
Ultimate Controlling Entity	SK Holdings Co., Ltd.	￦	—		3,519		149,574
Associates	HappyNarae Co., Ltd.		—		18		21,063
	F&U Credit information Co., Ltd.		—		34		1,328
	SK hynix Inc.		—		22,379		92
	Wave City Development Co., Ltd.		—		38,412		—
	Daehan Kanggun BcN Co., Ltd.(*)		22,147		—		—
	KEB HanaCard Co., Ltd.		—		1,619		7,676
	Xian Tianlong Science and Technology Co., Ltd.		8,287		—		—
	Others		813		4,191		945
			31,247		66,653		31,104
Other	SK Engineering & Construction Co., Ltd.		—		1,808		4,975
	SK Networks. Co., Ltd.		—		3,254		247,728
	SK Networks Services Co., Ltd.		—		13		13,913
	SK Telesys Co., Ltd.		—		20		24,918
	SK TNS Co., Ltd.		—		3		68,276
	SK Innovation Co., Ltd.		—		1,350		892
	SK Energy Co., Ltd.		—		1,213		113
	SK Gas Co., Ltd.		—		1,769		9
	Others		—		2,783		30,209
			—		12,213		391,033
Total		￦	31,247		82,385		571,711

(*) The Parent Company has recognized allowances for doubtful accounts on the entire balance of loans to Daehan Kanggun BcN Co., Ltd. as of December 31, 2016.

(5) SK m&service Co., Ltd., a subsidiary of the Parent Company, has entered into a performance agreement with SK Energy Co., Ltd. and provided a blank note to SK Energy Co., Ltd., with regard to this transaction.

(6) As of December 31, 2017, the Group provides with USD 12,240,000 of payment guarantees for the borrowings of the Celcom Planet, the joint ventures of the Group.

(7) There were additional investments in associates and joint ventures during the years ended December 31, 2017 and 2016 as presented in Note 12.

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Statements of Cash Flows (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Adjustments for income and expenses from operating activities

Adjustments for income and expenses from operating activities for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017			2016			2015
Interest income	￦	(76,045	)		(54,353	)		(45,884	)
Dividend		(12,416	)		(19,161	)		(16,102	)
Gain on foreign currency translation		(7,110	)		(5,085	)		(5,090	)
Gain on disposal of long-term investment securities		(4,890	)		(459,349	)		(10,786	)
Gain on valuation of derivatives		(223,943	)		(4,132	)		(1,927	)
Gain relating to investments in associates and joint ventures, net		(2,245,732	)		(544,501	)		(786,140	)
Gain on sale of accounts receivable — trade		(18,548	)		(18,638	)		—
Gain on disposal of property and equipment and intangible assets		(13,991	)		(6,908	)		(7,140	)
Gain relating to financial assets at fair value through profit or loss		(33	)		(25	)		—
Gain related to financial liabilities at fair value through profit or loss		—			(121	)		(5,188	)
Reversal of impairment loss on available-for-sale financial assets		(9,900	)		—			—
Other income		(1,129	)		(2,123	)		(7,577	)
Interest expenses		299,100			290,454			297,662
Loss on foreign currency translation		8,419			3,991			4,750
Loss on disposal of long-term investment securities		36,024			2,919			2,599
Other finance costs		14,519			5,255			21,787
Loss on sale of accounts receivable — trade		9,682			—			—
Loss on settlement of derivatives		10,031			3,428			4,845
Income tax expense		745,654			436,038			519,480
Expense related to defined benefit plan		127,696			118,143			110,021
Share option		414			—			—
Depreciation and amortization		3,247,519			3,068,558			2,993,486
Bad debt expense		34,584			37,820			60,450
Loss on disposal of property and equipment and intangible assets		60,086			63,797			21,392
Impairment loss on property and equipment and intangible assets		54,946			24,506			35,845
Loss relating to financial liabilities at fair value through profit or loss		678			4,018			526
Bad debt for accounts receivable — other		5,793			40,312			15,323
Loss on impairment of investment assets		9,003			24,033			42,966
Other expenses		46,353			30,685			4,845
	￦	2,096,764			3,039,561			3,250,143

Changes in assets and liabilities from operating activities

Changes in assets and liabilities from operating activities for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017			2016			2015
Accounts receivable — trade	￦	46,144			88,549			7,554
Accounts receivable — other		(159,960	)		(446,286	)		(11,108	)
Accrued income		14			445			116
Advance payments		(1,269	)		47,615			(35,906	)
Prepaid expenses		(28,362	)		(30,311	)		(40,464	)
Value-Added Tax refundable		(3,080	)		(4,587	)		1,385
Inventories		(17,958	)		798			(7,814	)
Long-term accounts receivable — other		(137,979	)		(147,117	)		—
Guarantee deposits		14,696			4,844			(11,238	)
Accounts payable — trade		(26,151	)		75,585			12,442
Accounts payable — other		134,542			316,464			(107,114	)
Advanced receipts		(13,470	)		37,429			6,421
Withholdings		(13,041	)		107,516			(191,209	)
Deposits received		(4,916	)		(2,153	)		(9,661	)
Accrued expenses		116,065			173,072			(28,845	)
Value-Added Tax payable		7,505			(4,072	)		3,494
Unearned revenue		(339	)		(36,209	)		(115,187	)
Provisions		(20,488	)		20,235			(30,562	)
Long-term provisions		(2,449	)		4,115			(4,447	)
Plan assets		(95,828	)		(125,440	)		(67,831	)
Retirement benefit payment		(60,883	)		(55,350	)		(58,513	)
Others		5,739			(11,378	)		2,753
		￦(261,468)			13,764			(685,734	)

Significant non-cash transactions

Significant non-cash transactions for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Increase of accounts payable — other related to acquisition of property and equipment and intangible assets	￦	44,214		1,511,913		39,973

Reconciliation of Lliabilities Arising from Financing Activities

Reconciliation of liabilities arising from financing activities for the year ended December 31, 2017 is as follows:

(In millions of won)
	January 1, 2017			Cash flows			Non-cash transactions								December 31, 2017
							Exchange rate changes			Fair value changes			Other changes
Total liabilities from financing activities
Short-term borrowings	￦	2,614			127,386			—			—			—		130,000
Long-term borrowings		172,906			87,299			(7,898	)		—			510		252,817
Debentures		7,194,207			130,558			(245,456	)		—			6,878		7,086,187
Long-term payables — other		1,918,024			(305,476	)		—			—			28,533		1,641,081
Derivative financial liabilities		87,153			(105,269	)		13,281			39,267			5,038		39,470
Derivative financial assets		(214,770	)		188			922			(40,235	)		682		(253,213	)
	￦	9,160,134			(65,314	)		(239,151	)		(968	)		41,641		8,896,342
Other cash flows from financing activities
Payments of cash dividends	￦				(706,091	)
Payments of interest on hybrid bond					(16,840	)
Transactions with non-controlling interests					(38,373	)
					(761,304	)
Total	￦				(826,618	)

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Cash Dividends paid to the Parent Company (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of Cash Dividends Received from Consolidated Subsidiaries and Associates

Cash dividends received from the consolidated subsidiaries and associates for the years ended December 31, 2017, 2016 and 2015 are as follows:

(In millions of won)
	2017		2016		2015
Cash dividends received from consolidated subsidiaries	￦	—		15,693		—
Cash dividends received from associates		89,063		79,132		46,390
	￦	89,063		94,825		46,390

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Reporting Entity - Total Issued Shares Held by Shareholders (Detail)	Dec. 31, 2017 shares
Disclosure of classes of share capital [line items]
Number of shares	80,745,711
Percentage of total shares issued (%)	100.00%
SK Holdings Co., Ltd. [member]
Disclosure of classes of share capital [line items]
Number of shares	20,363,452
Percentage of total shares issued (%)	25.22%
National pension service [member]
Disclosure of classes of share capital [line items]
Number of shares	7,392,350
Percentage of total shares issued (%)	9.16%
Institutional investors and other minority shareholders [member]
Disclosure of classes of share capital [line items]
Number of shares	42,853,358
Percentage of total shares issued (%)	53.07%
Treasury shares [member]
Disclosure of classes of share capital [line items]
Number of shares	10,136,551
Percentage of total shares issued (%)	12.55%

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Reporting Entity - List of Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
SK Telink Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Telink Co., Ltd.
Location	Korea
Primary business	Telecommunication and MVNO service
Ownership	100.00%	85.90%
SK Communications Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Communications Co., Ltd.
Location	Korea
Primary business	Internet website services
Ownership	100.00%	64.50%
SK Broadband Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Broadband Co., Ltd
Location	Korea
Primary business	Telecommunication services
Ownership	100.00%	100.00%
PS&Marketing Corporation [member]
Disclosure of subsidiaries [line items]
Subsidiary	PS&Marketing Corporation
Location	Korea
Primary business	Communications device retail business
Ownership	100.00%	100.00%
SERVICEACE Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SERVICEACE Co., Ltd.
Location	Korea
Primary business	Customer center management service
Ownership	100.00%	100.00%
SERVICE TOP Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SERVICE TOP Co., Ltd.
Location	Korea
Primary business	Customer center management service
Ownership	100.00%	100.00%
Network O&S Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	Network O&S Co., Ltd.
Location	Korea
Primary business	Base station maintenance service
Ownership	100.00%	100.00%
SK Planet Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Planet Co., Ltd.
Location	Korea
Primary business	Telecommunication service
Ownership	98.10%	98.10%
Iriver Limted [member]
Disclosure of subsidiaries [line items]
Subsidiary	IRIVER LIMITED
Location	Korea
Primary business	Manufacturing digital audio players and other portable media devices.
Ownership	45.90%	48.90%
SK Telecom China Holdings Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Telecom China Holdings Co., Ltd.
Location	China
Primary business	Investment
Ownership	100.00%	100.00%
SK Global Healthcare Business Group, Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Global Healthcare Business Group, Ltd.
Location	Hong Kong
Primary business	Investment
Ownership	100.00%	100.00%
SKT Vietnam PTE. Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SKT Vietnam PTE. Ltd.
Location	Singapore
Primary business	Telecommunication service
Ownership	73.30%	73.30%
SKT Americas, Inc. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SKT Americas, Inc.
Location	USA
Primary business	Information gathering and consulting
Ownership	100.00%	100.00%
YTK Investment Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	YTK Investment Ltd.
Location	Cayman Islands
Primary business	Investment association
Ownership	100.00%	100.00%
Atlas investment [member]
Disclosure of subsidiaries [line items]
Subsidiary	Atlas Investment
Location	Cayman Islands
Primary business	Investment association
Ownership	100.00%	100.00%
Entrix Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	Entrix Co., Ltd.
Location	Korea
Primary business	Cloud streaming services
Ownership		100.00%
SK techx Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK techx Co., Ltd.
Location	Korea
Primary business	System software development and supply
Ownership	100.00%	100.00%
One Store Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	One Store Co., Ltd.
Location	Korea
Primary business	Telecommunication services
Ownership	65.50%	65.50%
SK m&service Co., Ltd [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK m&service Co., Ltd. (formerly, M&Service Co., Ltd.)
Location	Korea
Primary business	Data base and internet website service
Ownership	100.00%	100.00%
SK Planet Japan, K. K. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Planet Japan, K. K.
Location	Japan
Primary business	Digital contents sourcing service
Ownership	79.50%	100.00%
SK Planet Global PTE. Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Planet Global PTE. Ltd.
Location	Singapore
Primary business	Digital contents sourcing service
Ownership	100.00%	100.00%
SKP GLOBAL HOLDINGS PTE. LTD. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SKP GLOBAL HOLDINGS PTE. LTD.
Location	Singapore
Primary business	Investment
Ownership	100.00%	100.00%
SKP America LLC. [member]
Disclosure of subsidiaries [line items]
Subsidiary	SKP America LLC.
Location	USA
Primary business	Digital contents sourcing service
Ownership	100.00%	100.00%
shopkick Management Company, Inc. [member]
Disclosure of subsidiaries [line items]
Subsidiary	shopkick Management Company, Inc.
Location	USA
Primary business	Investment
Ownership	100.00%	100.00%
shopkick, Inc. [member]
Disclosure of subsidiaries [line items]
Subsidiary	shopkick, Inc.
Location	USA
Primary business	Reward points-based in-store shopping app development
Ownership	100.00%	100.00%
Planet11 E-commerce Solutions India Pvt. Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	Planet11 E-commerceSolutions India Pvt. Ltd.
Location	India
Primary business	Electronic commerce platform service
Ownership		99.00%
11street [member]
Disclosure of subsidiaries [line items]
Subsidiary	11street (Thailand) Co., Ltd.
Location	Thailand
Primary business	Electronic commerce
Ownership	100.00%	100.00%
Hello Nature Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	Hello Nature Ltd.
Location	Korea
Primary business	Retail of agro-fisheries and livestock
Ownership	100.00%	100.00%
iriver Enterprise Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	iriver Enterprise Ltd.
Location	Hong Kong
Primary business	Management of Chinese subsidiary
Ownership	100.00%	100.00%
iriver Inc. [member]
Disclosure of subsidiaries [line items]
Subsidiary	iriver Inc.
Location	USA
Primary business	Marketing and sales in North America
Ownership	100.00%	100.00%
iriver China Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	iriver China Co., Ltd.
Location	China
Primary business	Sales and manufacturing MP3,4 in China
Ownership	100.00%	100.00%
Dongguan iriver Electronics Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	Dongguan iriver Electronics Co., Ltd.
Location	China
Primary business	Sales and manufacturing e-book in China
Ownership	100.00%	100.00%
groovers JP Ltd. [member]
Disclosure of subsidiaries [line items]
Subsidiary	groovers JP Ltd.
Location	Japan
Primary business	Digital music contents sourcing and distribution service
Ownership	100.00%	100.00%
S.M. LIFE DESIGN COMPANY JAPAN INC [member]
Disclosure of subsidiaries [line items]
Subsidiary	S.M. LIFE DESIGN COMPANY JAPAN INC.
Location	Japan
Primary business	Selling of goods in Japan
Ownership	100.00%
S.M. Mobile Communications JAPAN Inc [member]
Disclosure of subsidiaries [line items]
Subsidiary	S.M. Mobile Communications JAPAN Inc.
Location	Japan
Primary business	Digital contents service
Ownership	100.00%
NSOK Co., Ltd [member]
Disclosure of subsidiaries [line items]
Subsidiary	NSOK Co., Ltd. (formerly, Neosnetworks Co., Ltd.)
Location	Korea
Primary business	Guarding of facilities
Ownership	100.00%	100.00%
K-net culture and contents venture fund [member]
Disclosure of subsidiaries [line items]
Subsidiary	K-net Culture and Contents Venture Fund
Location	Korea
Primary business	Capital investing in startups
Ownership	59.00%	59.00%
Home and Service Co., Ltd [member]
Disclosure of subsidiaries [line items]
Subsidiary	Home & Service Co., Ltd.
Location	Korea
Primary business	Operation of information and communication facility
Ownership	100.00%
SK stoa Co., Ltd [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK stoa Co., Ltd
Location	Korea
Primary business	Other telecommunication retail business
Ownership	100.00%
SK Telecom Innovation Fund, L.P. (formerly, Technology Innovation Partners, L.P.) [member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Telecom Innovation Fund, L.P.
Location	USA
Primary business	Investment
Ownership	100.00%	100.00%
SK Telecom China Fund I L.P. [Member]
Disclosure of subsidiaries [line items]
Subsidiary	SK Telecom China Fund I L.P.
Location	Cayman Islands
Primary business	Investment
Ownership	100.00%	100.00%
Stonebridge Cinema Fund [Member]
Disclosure of subsidiaries [line items]
Subsidiary	Stonebridge Cinema Fund
Location	Korea
Primary business	Capital investing in startups
Ownership		60.00%

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Reporting Entity - List of Subsidiaries (Parenthetical) (Detail) - KRW (₩) ₩ / shares in Units, ₩ in Millions			12 Months Ended
	Dec. 14, 2017	Feb. 07, 2017	Dec. 31, 2017
SK Telink Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Price per share in cash of shares acquired	₩ 270,583
Number of shares acquired, purchase price	₩ 35,281
SK Communications Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Price per share in cash of shares acquired		₩ 2,814
Number of shares acquired, purchase price		₩ 41,550
Iriver Limted [member] | Top of range [member]
Disclosure of subsidiaries [line items]
Percentage of voting rights			50.00%

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Reporting Entity - Condensed Financial Information of the Significant Subsidiaries (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of subsidiaries [line items]
Total assets	₩ 33,428,669	₩ 31,297,663
Total liabilities	15,399,474	15,181,233
Total equity (deficit)	18,029,195	16,116,430	₩ 15,374,096	₩ 15,248,270
Revenue	17,552,010	17,158,364	17,167,669
Profit (loss)	2,657,595	1,660,101	1,515,885
SK Telink Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	455,685	440,956	309,955
Total liabilities	104,727	122,741	113,878
Total equity (deficit)	350,958	318,215	196,077
Revenue	389,944	406,930	431,368
Profit (loss)	32,728	61,585	55,781
SK m&service Co., Ltd [member]
Disclosure of subsidiaries [line items]
Total assets	113,515	107,768	89,452
Total liabilities	62,795	56,596	42,414
Total equity (deficit)	50,720	51,172	47,038
Revenue	193,256	173,816	143,255
Profit (loss)	1,249	4,958	5,549
SK Communications Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	90,923	128,233	152,496
Total liabilities	28,410	31,592	35,014
Total equity (deficit)	62,513	96,641	117,482
Revenue	47,546	58,154	80,147
Profit (loss)	(35,454)	(20,411)	(14,826)
SK Broadband Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	3,802,349	3,523,494	3,291,707
Total liabilities	2,616,317	2,376,429	2,170,484
Total equity (deficit)	1,186,032	1,147,065	1,121,223
Revenue	3,050,083	2,942,976	2,731,344
Profit (loss)	32,030	21,526	10,832
K-net culture and contents venture fund [member]
Disclosure of subsidiaries [line items]
Total assets	250,747
Total liabilities	35,900
Total equity (deficit)	214,847
Profit (loss)	196,250
PS&Marketing Corporation [member]
Disclosure of subsidiaries [line items]
Total assets	506,883	546,803	509,580
Total liabilities	288,881	328,846	300,364
Total equity (deficit)	218,002	217,957	209,216
Revenue	1,766,142	1,679,735	1,791,944
Profit (loss)	391	11,908	4,835
SERVICEACE Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	77,681	67,735	65,424
Total liabilities	45,501	40,014	34,240
Total equity (deficit)	32,180	27,721	31,184
Revenue	197,408	199,828	206,338
Profit (loss)	2,599	3,605	2,778
SERVICE TOP Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	65,406	59,004	61,897
Total liabilities	41,860	39,121	38,482
Total equity (deficit)	23,546	19,883	23,415
Revenue	186,117	186,740	197,092
Profit (loss)	3,309	3,971	4,396
Network O&S Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	87,000	69,774	77,426
Total liabilities	45,248	35,798	48,069
Total equity (deficit)	41,752	33,976	29,357
Revenue	255,841	218,917	210,676
Profit (loss)	6,283	3,755	6,466
SK Planet Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	1,534,866	1,935,663	2,406,988
Total liabilities	920,677	834,151	784,631
Total equity (deficit)	614,189	1,101,512	1,622,357
Revenue	1,082,685	1,177,323	1,624,630
Profit (loss)	(513,667)	(30,959)	(75,111)
Iriver Limted [member]
Disclosure of subsidiaries [line items]
Total assets	130,878	50,075	60,434
Total liabilities	17,204	11,941	12,377
Total equity (deficit)	113,674	38,134	48,057
Revenue	69,452	52,328	55,637
Profit (loss)	(14,092)	(9,987)	635
SKT Americas, Inc. [member]
Disclosure of subsidiaries [line items]
Total assets	412,251	439,209	380,141
Total equity (deficit)	412,251	439,209	380,141
Profit (loss)	(57)	1,226	791
SK techx Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	237,700	212,819
Total liabilities	41,561	52,563
Total equity (deficit)	196,139	160,256
Revenue	195,948	193,396
Profit (loss)	26,827	28,213
One Store Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets	104,891	134,207
Total liabilities	39,874	41,738
Total equity (deficit)	65,017	92,469
Revenue	115,596	106,809
Profit (loss)	(27,254)	(22,161)
Home and Service Co., Ltd [member]
Disclosure of subsidiaries [line items]
Total assets	83,698
Total liabilities	38,350
Total equity (deficit)	45,348
Revenue	141,739
Profit (loss)	11
Entrix Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Total assets			30,876
Total liabilities			3,186
Total equity (deficit)			27,690
Revenue			4,895
Profit (loss)			(1,826)
shopkick Management Company, Inc. [member]
Disclosure of subsidiaries [line items]
Total assets	338,650	354,627	306,248
Total liabilities			7
Total equity (deficit)	338,650	354,627	306,241
Revenue			7
Profit (loss)	(238)	(85)	(2,455)
shopkick, Inc. [member]
Disclosure of subsidiaries [line items]
Total assets	37,336	37,947	25,388
Total liabilities	32,219	34,024	32,243
Total equity (deficit)	5,117	3,923	(6,855)
Revenue	48,836	45,876	33,851
Profit (loss)	₩ (25,249)	₩ (27,149)	₩ (52,390)

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Reporting Entity - Additional Information (Detail) - KRW (₩)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsidiaries [member]
Disclosure of subsidiaries [line items]
Dividends paid by subsidiaries of which non-controlling interests are significant	₩ 0	₩ 0	₩ 0

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Reporting Entity - Information of Significant Non-controlling Interests of the Group (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of subsidiaries [line items]
Current assets	₩ 6,201,799	₩ 5,996,628
Non-current assets	27,226,870	25,301,035
Current liabilities	(7,109,123)	(6,444,099)
Non-current liabilities	(8,290,351)	(8,737,134)
Carrying amount of non-controlling interests	187,056	145,031
Revenue	17,552,010	17,158,364	₩ 17,167,669
Profit (loss) for the period	2,657,595	1,660,101	1,515,885
Total comprehensive income (loss)	2,656,582	1,412,770	1,517,720
Profit (loss) attributable to non-controlling interests	57,766	(15,866)	(2,719)
Net cash provided by (used in) operating activities	3,855,820	4,243,168	3,778,129
Net cash provided by (used in) investing activities	(3,070,607)	(2,462,208)	(2,880,499)
Net cash provided by (used in) financing activities	₩ (826,618)	(1,044,829)	(964,583)
K-net culture and contents venture fund [member]
Disclosure of subsidiaries [line items]
Ownership of non-controlling interests (%)	41.00%
Current assets	₩ 625
Non-current assets	250,122
Current liabilities	(35,900)
Net assets	214,847
Carrying amount of non-controlling interests	88,087
Profit (loss) for the period	196,250
Total comprehensive income (loss)	201,693
Profit (loss) attributable to non-controlling interests	80,463
Net cash provided by (used in) operating activities	(7)
Net cash provided by (used in) investing activities	(600)
Net increase (decrease) in cash and cash equivalents	₩ (607)
Iriver Limted [member]
Disclosure of subsidiaries [line items]
Ownership of non-controlling interests (%)	54.10%
Current assets	₩ 74,873
Non-current assets	56,005
Current liabilities	(9,563)
Non-current liabilities	(7,641)
Net assets	113,674
Carrying amount of non-controlling interests	63,382
Revenue	69,452	52,328	55,637
Profit (loss) for the period	(14,092)	₩ (9,987)	₩ 635
Total comprehensive income (loss)	(14,278)
Profit (loss) attributable to non-controlling interests	(7,438)
Net cash provided by (used in) operating activities	(7,553)
Net cash provided by (used in) investing activities	(45,002)
Net cash provided by (used in) financing activities	64,571
Net increase (decrease) in cash and cash equivalents	12,016
SK Communications Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Ownership of non-controlling interests (%)		35.46%	35.46%
Current assets		₩ 81,806	₩ 95,662
Non-current assets		46,427	56,834
Current liabilities		(30,098)	(33,306)
Non-current liabilities		(1,494)	(1,708)
Net assets		96,641	117,482
Carrying amount of non-controlling interests		34,265	41,659
Revenue	47,546	58,154	80,147
Profit (loss) for the period	₩ (35,454)	(20,411)	(14,826)
Total comprehensive income (loss)		20,841	16,698
Profit (loss) attributable to non-controlling interests		7,240	5,254
Net cash provided by (used in) operating activities		(4,891)	(2,706)
Net cash provided by (used in) investing activities		3,625	8,723
Net increase (decrease) in cash and cash equivalents		₩ (1,266)	₩ 6,017
One Store Co., Ltd. [member]
Disclosure of subsidiaries [line items]
Ownership of non-controlling interests (%)	34.46%	34.46%
Current assets	₩ 76,810	₩ 90,414
Non-current assets	28,081	43,793
Current liabilities	(38,547)	(40,969)
Non-current liabilities	(1,327)	(769)
Net assets	65,017	92,469
Carrying amount of non-controlling interests	22,405	31,863
Revenue	115,596	106,809
Profit (loss) for the period	(27,254)	(22,161)
Total comprehensive income (loss)	(27,452)	22,402
Profit (loss) attributable to non-controlling interests	(9,392)	6,772
Net cash provided by (used in) operating activities	13,912	(4,447)
Net cash provided by (used in) investing activities	(2,000)	(20,796)
Net cash provided by (used in) financing activities	(7)	51,426
Net increase (decrease) in cash and cash equivalents	₩ 11,905	₩ 26,183

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Significant Accounting Policies - Estimated Useful Lives of the Group's Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Bottom of range [member] | Buildings and structures [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives (years)	15 Years
Bottom of range [member] | Machinery [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives (years)	3 Years
Bottom of range [member] | Other property and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives (years)	2 Years
Top of range [member] | Buildings and structures [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives (years)	40 Years
Top of range [member] | Machinery [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives (years)	15 Years
Top of range [member] | Other property and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives (years)	10 Years

XML

Significant Accounting Policies - Estimated Useful Lives of the Group's Intangible Assets (Detail)	12 Months Ended
	Dec. 31, 2017
Frequency usage rights [member] | Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	5 Years
Frequency usage rights [member] | Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	13 Years
Land usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	5 Years
Industrial rights [member] | Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	5 Years
Industrial rights [member] | Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	10 Years
Development costs [member] | Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	3 Years
Development costs [member] | Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	5 Years
Facility usage rights [member] | Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	10 Years
Facility usage rights [member] | Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	20 Years
Customer relations [member] | Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	3 Years
Customer relations [member] | Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	7 Years
Other [member] | Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	3 Years
Other [member] | Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Useful lives (years)	20 Years

XML

Significant Accounting Policies - Additional Information (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reclassification of financial assets [line items]
Financial asset	₩ 7,461,181	₩ 7,088,162
Financial asset	887,007	828,521
Financial liabilities	12,725,704	12,702,059
Loss allowances for financial assets	(4,100,838)	(3,962,560)
Changes in fair value of cash flow hedge was recognized in OCI	73,828
Financial liabilities at fair value through profit or loss [member]
Disclosure of reclassification of financial assets [line items]
Financial liabilities	60,278	59,600
New IFRSs nine [member]
Disclosure of reclassification of financial assets [line items]
Hedged liabilities		2,026,434
Investment bonds [member]
Disclosure of reclassification of financial assets [line items]
Financial asset	19,928	6,755
Financial assets are measured at FVTPL	97,003
Allowance for doubtful accounts [Member]
Disclosure of reclassification of financial assets [line items]
Loss allowances for financial assets	362,171	369,332
Loans and receivables [member]
Disclosure of reclassification of financial assets [line items]
Financial asset	6,176,575	5,937,507
Loans and receivables [member] | Financial assets at amortised cost, class [member]
Disclosure of reclassification of financial assets [line items]
Financial asset	6,176,575
Available- for-sale financial assets [Member]
Disclosure of reclassification of financial assets [line items]
Financial asset	934,390	935,885
Financial asset	887,007	828,521
Available- for-sale financial assets [Member] | Equity investments [member] | New IFRSs nine [member]
Disclosure of reclassification of financial assets [line items]
Financial asset	914,462
Financial assets at fair value through profit or loss [member]
Disclosure of reclassification of financial assets [line items]
Financial asset	₩ 328,314	₩ 7,368
Bottom of range [member]
Disclosure of reclassification of financial assets [line items]
Investment property, estimated useful lives	15 Years
Top of range [member]
Disclosure of reclassification of financial assets [line items]
Investment property, estimated useful lives	40 Years

XML

Operating Segments - Segment Information (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Revenue	₩ 17,520,013	₩ 17,091,816	₩ 17,136,734
Depreciation and amortization	3,097,466	2,941,886	2,845,295
Operating profit (loss)	1,224,572	1,303,418	1,495,425
Gain relating to investments in subsidiaries, associates and joint ventures, net	2,245,732	544,501	786,140
Finance income	366,561	575,050	103,900
Finance costs	(433,616)	(326,830)	(350,100)
Profit before income tax	3,403,249	2,096,139	2,035,365
External [member]
Disclosure of operating segments [line items]
Revenue	17,520,013	17,091,816	17,136,734
Operating segments [member]
Disclosure of operating segments [line items]
Revenue	20,341,169	19,889,322	20,238,944
Depreciation and amortization	3,097,466	2,941,886	2,845,295
Operating profit (loss)	1,536,626	1,535,744	1,708,006
Operating segments [member] | Intersegment [member]
Disclosure of operating segments [line items]
Revenue	2,821,156	2,797,506	3,102,210
Operating segments [member] | External [member]
Disclosure of operating segments [line items]
Revenue	17,520,013	17,091,816	17,136,734
Operating segments [member] | Cellular Services [member]
Disclosure of operating segments [line items]
Revenue	14,873,543	14,635,720	14,962,689
Depreciation and amortization	2,390,016	2,262,363	2,174,819
Operating profit (loss)	1,714,078	1,799,127	1,678,339
Operating segments [member] | Cellular Services [member] | Intersegment [member]
Disclosure of operating segments [line items]
Revenue	1,611,408	1,630,811	1,693,411
Operating segments [member] | Cellular Services [member] | External [member]
Disclosure of operating segments [line items]
Revenue	13,262,135	13,004,909	13,269,278
Operating segments [member] | Fixed-line telecommunication services [member]
Disclosure of operating segments [line items]
Revenue	3,586,887	3,349,905	3,162,712
Depreciation and amortization	592,877	551,811	531,106
Operating profit (loss)	167,515	132,459	108,252
Operating segments [member] | Fixed-line telecommunication services [member] | Intersegment [member]
Disclosure of operating segments [line items]
Revenue	862,736	698,712	668,139
Operating segments [member] | Fixed-line telecommunication services [member] | External [member]
Disclosure of operating segments [line items]
Revenue	2,724,151	2,651,193	2,494,573
Operating segments [member] | E-commerce services [member]
Disclosure of operating segments [line items]
Revenue	1,091,903	1,177,323	1,703,278
Depreciation and amortization	54,486	68,298	112,537
Operating profit (loss)	(267,829)	(365,194)	(6,740)
Operating segments [member] | E-commerce services [member] | Intersegment [member]
Disclosure of operating segments [line items]
Revenue	47,732	176,007	643,299
Operating segments [member] | E-commerce services [member] | External [member]
Disclosure of operating segments [line items]
Revenue	1,044,171	1,001,316	1,059,979
Operating segments [member] | Others [member]
Disclosure of operating segments [line items]
Revenue	788,836	726,374	410,265
Depreciation and amortization	60,087	59,414	26,833
Operating profit (loss)	(77,138)	(30,648)	(71,845)
Operating segments [member] | Others [member] | Intersegment [member]
Disclosure of operating segments [line items]
Revenue	299,280	291,976	97,361
Operating segments [member] | Others [member] | External [member]
Disclosure of operating segments [line items]
Revenue	489,556	434,398	312,904
Adjustments [member]
Disclosure of operating segments [line items]
Revenue	(2,821,156)	(2,797,506)	(3,102,210)
Operating profit (loss)	(312,054)	(232,326)	(212,581)
Adjustments [member] | Intersegment [member]
Disclosure of operating segments [line items]
Revenue	₩ (2,821,156)	₩ (2,797,506)	₩ (3,102,210)

XML

Operating Segments - Reconciliation of Total Segment Operating Income to Consolidated Operating Profit from Continuing Operations (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Operating income	₩ 1,224,572	₩ 1,303,418	₩ 1,495,425
Gain on disposal of property and equipment and intangible assets	13,991	6,908	7,140
Others	18,006	59,640	23,795
Other operating income	31,997	66,548	30,935
Impairment loss on property and equipment and intangible assets	(54,946)	(24,506)	(35,845)
Loss on disposal of property and equipment and intangible assets	(60,086)	(63,797)	(21,392)
Donations	(112,634)	(96,633)	(72,454)
Bad debt for accounts receivable - other	(5,793)	(40,312)	(15,323)
Others	(101,589)	(49,593)	(55,536)
Other operating expenses	(1,630,747)	(1,523,766)	(1,524,377)
Penalty refund		25,000
Penalties and various other expenses	21,400	7,600	29,500
Operating segments [member]
Disclosure of operating segments [line items]
Operating income	1,536,626	1,535,744	1,708,006
Adjustments [member]
Disclosure of operating segments [line items]
Operating income	(312,054)	(232,326)	(212,581)
Gain on disposal of property and equipment and intangible assets	13,991	6,908	7,140
Others	18,006	59,640	23,795
Other operating income	31,997	66,548	30,935
Impairment loss on property and equipment and intangible assets	(54,946)	(24,506)	(35,845)
Loss on disposal of property and equipment and intangible assets	(60,086)	(63,797)	(21,392)
Donations	(112,634)	(96,633)	(72,454)
Bad debt for accounts receivable - other	(5,793)	(40,312)	(15,323)
Others	(110,592)	(73,626)	(98,502)
Other operating expenses	₩ (344,051)	₩ (298,874)	₩ (243,516)

XML

Operating Segments - Additional Information (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Revenue	₩ 17,520,013	₩ 17,091,816	₩ 17,136,734
Domestic [member]
Disclosure of operating segments [line items]
Revenue	17,374,000	16,940,000	17,083,000
Non-current assets	15,554,000	15,949,000	14,474,000
Outside of Korea [member]
Disclosure of operating segments [line items]
Non-current assets	₩ 257,000	₩ 286,000	₩ 287,000

XML

Operating Segments - Operating Revenue by Service Type (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Revenue	₩ 17,520,013	₩ 17,091,816	₩ 17,136,734
External [member]
Disclosure of operating segments [line items]
Revenue	17,520,013	17,091,816	17,136,734
Operating segments [member]
Disclosure of operating segments [line items]
Revenue	20,341,169	19,889,322	20,238,944
Operating segments [member] | External [member]
Disclosure of operating segments [line items]
Revenue	17,520,013	17,091,816	17,136,734
Operating segments [member] | Cellular Services [member]
Disclosure of operating segments [line items]
Revenue	14,873,543	14,635,720	14,962,689
Operating segments [member] | Cellular Services [member] | External [member]
Disclosure of operating segments [line items]
Revenue	13,262,135	13,004,909	13,269,278
Operating segments [member] | Cellular Services [member] | External [member] | Wireless service [member]
Disclosure of operating segments [line items]
Revenue	10,638,961	10,582,963	10,720,518
Operating segments [member] | Cellular Services [member] | External [member] | Cellular interconnection [member]
Disclosure of operating segments [line items]
Revenue	592,754	614,446	710,026
Operating segments [member] | Cellular Services [member] | External [member] | Wireless device sales [member]
Disclosure of operating segments [line items]
Revenue	1,052,203	922,449	963,354
Operating segments [member] | Cellular Services [member] | External [member] | Miscellaneous [member]
Disclosure of operating segments [line items]
Revenue	978,217	885,051	875,380
Operating segments [member] | Fixed-line telecommunication services [member]
Disclosure of operating segments [line items]
Revenue	3,586,887	3,349,905	3,162,712
Operating segments [member] | Fixed-line telecommunication services [member] | External [member]
Disclosure of operating segments [line items]
Revenue	2,724,151	2,651,193	2,494,573
Operating segments [member] | Fixed-line telecommunication services [member] | External [member] | Fixed line telephone service [member]
Disclosure of operating segments [line items]
Revenue	316,763	357,754	420,611
Operating segments [member] | Fixed-line telecommunication services [member] | External [member] | Fixed line interconnection [member]
Disclosure of operating segments [line items]
Revenue	116,070	134,089	57,130
Operating segments [member] | Fixed-line telecommunication services [member] | External [member] | Broadband internet service and advanced media platform service [member]
Disclosure of operating segments [line items]
Revenue	1,641,645	1,472,776	1,308,789
Operating segments [member] | Fixed-line telecommunication services [member] | External [member] | International calling service [member]
Disclosure of operating segments [line items]
Revenue	89,412	95,986	99,106
Operating segments [member] | Fixed-line telecommunication services [member] | External [member] | Miscellaneous [member]
Disclosure of operating segments [line items]
Revenue	560,261	590,588	608,937
Operating segments [member] | E-commerce services [member]
Disclosure of operating segments [line items]
Revenue	1,091,903	1,177,323	1,703,278
Operating segments [member] | E-commerce services [member] | External [member]
Disclosure of operating segments [line items]
Revenue	1,044,171	1,001,316	1,059,979
Operating segments [member] | Others [member]
Disclosure of operating segments [line items]
Revenue	788,836	726,374	410,265
Operating segments [member] | Others [member] | External [member]
Disclosure of operating segments [line items]
Revenue	489,556	434,398	312,904
Operating segments [member] | Others [member] | External [member] | Portal service [member]
Disclosure of operating segments [line items]
Revenue	43,952	54,177	71,812
Operating segments [member] | Others [member] | External [member] | Miscellaneous [member]
Disclosure of operating segments [line items]
Revenue	₩ 445,604	₩ 380,221	₩ 241,092

XML

Restricted Deposits - Deposits Which are Restricted in Use (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [line items]
Short-term financial instruments	₩ 616,780	₩ 468,768
Long-term financial instruments	1,222	937
Financial instruments	618,002	469,705
Restricted deposits [member]
Disclosure of financial assets [line items]
Short-term financial instruments	89,850	90,278
Long-term financial instruments	1,222	937
Financial instruments	₩ 91,072	₩ 91,215

XML

Trade and Other Receivables - Details of Trade and Other Receivables (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [line items]
Accounts receivable - trade	₩ 2,126,007	₩ 2,240,926
Short-term loans	62,830	58,979
Accounts receivable - other	1,260,835	1,121,444
Accrued income	3,979	2,780
Others	3,927	3,937
Trade and other receivables, current	3,457,578	3,428,066
Long-term loans	50,874	65,476
Long-term accounts receivable - other	287,048	149,669
Guarantee deposits	292,590	298,964
Long-term accounts receivable - trade	12,748	20,385
Trade and other receivables, noncurrent	643,260	534,494
Trade and other receivables	4,100,838	3,962,560
Gross amount [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	2,365,270	2,482,502
Short-term loans	63,380	59,526
Accounts receivable - other	1,336,247	1,200,421
Accrued income	3,979	2,780
Others	3,927	3,937
Trade and other receivables, current	3,772,803	3,749,166
Long-term loans	97,635	113,456
Long-term accounts receivable - other	287,048	149,669
Guarantee deposits	292,590	298,964
Long-term accounts receivable - trade	12,933	20,637
Trade and other receivables, noncurrent	690,206	582,726
Trade and other receivables	4,463,009	4,331,892
Allowance for doubtful accounts [Member]
Disclosure of financial assets [line items]
Accounts receivable - trade	(239,263)	(241,576)
Short-term loans	(550)	(547)
Accounts receivable - other	(75,412)	(78,977)
Trade and other receivables, current	(315,225)	(321,100)
Long-term loans	(46,761)	(47,980)
Long-term accounts receivable - trade	(185)	(252)
Trade and other receivables, noncurrent	(46,946)	(48,232)
Trade and other receivables	₩ (362,171)	₩ (369,332)

XML

Trade and Other Receivables - Changes in Allowances for Doubtful Accounts of Trade and Other Receivables (Detail) - Trade and other receivables [member] - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [line items]
Beginning balance	₩ 369,332	₩ 344,016
Bad debt expense	40,377	78,132
Write-offs	(70,802)	(79,891)
Other	23,264	27,075
Ending balance	₩ 362,171	₩ 369,332

XML

Trade and Other Receivables - Details of Overdue but Not Impaired, and Impaired Trade and Other Receivables (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [line items]
Accounts receivable - trade	₩ 2,138,755	₩ 2,261,311
Other receivables	1,962,083	1,701,249
Overdue but not impaired [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	29,304	41,613
Other receivables	3,113	5,663
Gross amount [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	2,378,203	2,503,139
Other receivables	2,084,806	1,828,753
Gross amount [member] | Neither overdue nor impaired [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	1,585,714	1,715,966
Other receivables	1,930,261	1,617,349
Gross amount [member] | Overdue but not impaired [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	29,304	41,613
Other receivables	3,113	5,663
Gross amount [member] | Impaired [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	763,185	745,560
Other receivables	151,432	205,741
Allowance for doubtful accounts [Member]
Disclosure of financial assets [line items]
Accounts receivable - trade	(239,448)	(241,828)
Other receivables	₩ (122,723)	₩ (127,504)

XML

Trade and Other Receivables - Aging of Overdue but Not Impaired Accounts Receivable (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [line items]
Accounts receivable - trade	₩ 2,138,755	₩ 2,261,311
Other receivables	1,962,083	1,701,249
Overdue but not impaired [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	29,304	41,613
Other receivables	3,113	5,663
Overdue but not impaired [member] | Less than 1 month [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	7,150	11,543
Other receivables	2,679	2,838
Overdue but not impaired [member] | 1 ~ 3 months [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	1,663	9,144
Other receivables	44	140
Overdue but not impaired [member] | 3 ~ 6 months [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	1,576	4,643
Other receivables	124	1
Overdue but not impaired [member] | More than 6 months [member]
Disclosure of financial assets [line items]
Accounts receivable - trade	18,915	16,283
Other receivables	₩ 266	₩ 2,684

XML

Inventories - Details of Inventories (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of inventories [Line Items]
Merchandise	₩ 243,975	₩ 225,958
Finished goods	1,332	1,568
Work-in-process	950	2,548
Raw materials and supplies	26,146	29,772
Inventories	272,403	259,846
Gross amount [member]
Disclosure of inventories [Line Items]
Merchandise	251,463	232,871
Finished goods	1,889	1,931
Work-in-process	1,906	2,895
Raw materials and supplies	29,395	31,141
Inventories	284,653	268,838
Accumulated impairment [member]
Disclosure of inventories [Line Items]
Merchandise	(7,488)	(6,913)
Finished goods	(557)	(363)
Work-in-process	(956)	(347)
Raw materials and supplies	(3,249)	(1,369)
Inventories	₩ (12,250)	₩ (8,992)

XML

Inventories - Amount of the Inventory Write-downs Charged to the Consolidated Statement of Income and Write-off of Inventories (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Classes of current inventories [abstract]
Charged to cost of products that have been resold	₩ 6,079	₩ 3,751	₩ 1,983
Write-off upon sale	₩ (2,820)	₩ (1,299)	₩ (2,095)

XML

Inventories - Additional Information (Detail) - KRW (₩)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Classes of current inventories [abstract]
Reversals of inventory write-downs	₩ 0	₩ 0	₩ 0

XML

Investment Securities - Details of Short-term Investment Securities (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [line items]
Short-term investment securities	₩ 144,386	₩ 107,364
Beneficiary certificates [member]
Disclosure of financial assets [line items]
Short-term investment securities	₩ 144,386	₩ 107,364

XML

Investment Securities - Details of Long-term Investment Securities (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of financial assets [line items]
Long-term investment securities	₩ 887,007	₩ 828,521
Sale of shares, amount of cash	129,726	555,519	₩ 149,310
Sale of shares, gain on disposal of long-term investment securities	₩ 4,890	₩ 459,349	₩ 10,786
Loen Entertainment, Inc. [member]
Disclosure of financial assets [line items]
Sale of shares, number of shares sold		3,793,756
Sale of shares, gain on disposal of long-term investment securities		₩ 314,745
Kakao Corp. [member]
Disclosure of financial assets [line items]
Sale of shares, number of shares exchanged	1,357,367	1,357,367
Sale of shares, amount of cash	₩ 112,649	₩ 218,037
POSCO Co., Ltd. [member]
Disclosure of financial assets [line items]
Sale of shares, amount of cash		305,110
Sale of shares, gain on disposal of long-term investment securities		138,779
Marketable equity securities [member]
Disclosure of financial assets [line items]
Long-term investment securities	589,202	526,363
Unlisted equity securities [member]
Disclosure of financial assets [line items]
Long-term investment securities	277,877	295,403
Equity securities [member]
Disclosure of financial assets [line items]
Long-term investment securities	867,079	821,766
Investment bonds [member]
Disclosure of financial assets [line items]
Long-term investment securities	₩ 19,928	₩ 6,755

XML

Investment Securities - Additional Information (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of financial assets [line items]
Sale of shares, amount of cash	₩ 129,726	₩ 555,519	₩ 149,310
Kakao Corp. [member]
Disclosure of financial assets [line items]
Sale of shares, number of shares exchanged	1,357,367	1,357,367
Sale of shares, amount of cash	₩ 112,649	₩ 218,037
Sale of shares, loss on disposal of long-term investment securities	₩ 35,468

XML

Business Combination - Additional information (Detail) - KRW (₩) ₩ in Millions	2 Months Ended	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Oct. 01, 2017	Sep. 01, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about business combination [line items]
Goodwill	₩ 1,915,017	₩ 1,915,017			₩ 1,932,452	₩ 1,908,590
S.M. LIFE DESIGN COMPANY JAPAN INC [member]
Disclosure of detailed information about business combination [line items]
Consideration transferred in cash				₩ 30,000
S.M. LIFE DESIGN COMPANY JAPAN INC [member] | Iriver Limted [member]
Disclosure of detailed information about business combination [line items]
Consideration transferred in cash				30,000
Goodwill				₩ 21,748
Revenue of acquiree since acquisition date		6,365
Profit (loss) of acquiree since acquisition date		₩ 1,244
S.M. Mobile Communications JAPAN Inc [member] | Iriver Limted [member]
Disclosure of detailed information about business combination [line items]
Goodwill			₩ 13,473
Revenue of acquiree since acquisition date	0
Profit (loss) of acquiree since acquisition date	₩ (103)

XML

Business Combination - Considerations Paid and Assets in Succession Recognized at the Acquisition Date (Detail) - KRW (₩) ₩ in Millions	Oct. 01, 2017	Sep. 01, 2017	Apr. 01, 2015
S.M. LIFE DESIGN COMPANY JAPAN INC [member]
Considerations paid and liabilities assumed:
Cash and cash equivalents		₩ 30,000
Assets and liabilities acquired:
Cash and cash equivalents		3,434
Trade and other receivables		1,471
Inventories		1,879
Property and equipment		4
Intangible assets		6,677
Trade and other payables		(2,563)
Deferred tax liabilities		(2,324)
Other liabilities		(326)
Net assets		₩ 8,252
S.M. Mobile Communications JAPAN Inc [member]
Considerations paid and liabilities assumed:
Shares of IRIVER LIMITED	₩ 24,650
Assets and liabilities acquired:
Cash and cash equivalents	4,112
Trade and other receivables	237
Property and equipment	311
Intangible assets	7,445
Other assets	41
Trade and other payables	(815)
Other liabilities	(154)
Net assets	₩ 11,177
Joeun Safe Co., Ltd [member]
Considerations paid and liabilities assumed:
Cash and cash equivalents			₩ 13,197
Accounts payable - other			1,858
Considerations paid and liabilities assumed			15,055
Assets and liabilities acquired:
Property and equipment			3,208
Intangible assets			8,486
Other assets			1,603
Net assets			₩ 13,297

XML

Investments in Associates and Joint Ventures - Investments in Associates and Joint Ventures Accounted for using the Equity Method (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Carrying amount	₩ 9,498,381	₩ 7,306,816
Joint ventures, Carrying amount	40,057	97,507
Investments in associates and joint ventures	₩ 9,538,438	₩ 7,404,323	₩ 6,896,293
Dogus Planet, Inc. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Joint ventures, Country	Turkey
Joint ventures, Ownership (%)	50.00%	50.00%
Joint ventures, Carrying amount	₩ 13,991	₩ 20,081
Investments in associates and joint ventures	₩ 13,991	₩ 20,081	15,118
PT XL planet digital [member]
Disclosure of investments in associates and joint ventures [Line Items]
Joint ventures, Country	Indonesia
Joint ventures, Ownership (%)		50.00%
Joint ventures, Carrying amount		₩ 27,512
Investments in associates and joint ventures		₩ 27,512	23,108
Finnq Co. Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Joint ventures, Country	Korea
Joint ventures, Ownership (%)	49.00%	49.00%
Joint ventures, Carrying amount	₩ 16,474	₩ 24,174
Investments in associates and joint ventures	₩ 16,474	24,174
Celcom Planet and others [member]
Disclosure of investments in associates and joint ventures [Line Items]
Joint ventures, Country	-
Joint ventures, Carrying amount	₩ 9,592	25,740
Investments in associates and joint ventures	₩ 9,592	₩ 25,740	3,406
SK China Company Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	China
Associates, Ownership (%)	27.30%	9.60%
Associates, Carrying amount	₩ 526,099	₩ 46,354
Investments in associates and joint ventures	₩ 526,099	₩ 46,354	43,814
Korea IT fund [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Korea
Associates, Ownership (%)	63.30%	63.30%
Associates, Carrying amount	₩ 257,003	₩ 263,850
Investments in associates and joint ventures	₩ 257,003	₩ 263,850	260,456
KEB HanaCard Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Korea
Associates, Ownership (%)	15.00%	15.00%
Associates, Carrying amount	₩ 280,988	₩ 265,798
Investments in associates and joint ventures	₩ 280,988	₩ 265,798	254,177
NanoEnTek, Inc. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Korea
Associates, Ownership (%)	28.50%	28.50%
Associates, Carrying amount	₩ 38,718	₩ 39,514
Investments in associates and joint ventures	₩ 38,718	₩ 39,514	45,008
SK Industrial Development China Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Hong Kong
Associates, Ownership (%)		21.00%
Associates, Carrying amount		₩ 74,717
Investments in associates and joint ventures		₩ 74,717	86,324
SK Technology Innovation Company [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Cayman Islands
Associates, Ownership (%)	49.00%	49.00%
Associates, Carrying amount	₩ 42,511	₩ 47,488
Investments in associates and joint ventures	₩ 42,511	₩ 47,488	45,891
HappyNarae Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Korea
Associates, Ownership (%)	45.00%	42.50%
Associates, Carrying amount	₩ 21,873	₩ 17,236
Investments in associates and joint ventures	₩ 21,873	₩ 17,236	17,095
SK hynix Inc. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Korea
Associates, Ownership (%)	20.10%	20.10%
Associates, Carrying amount	₩ 8,130,000	₩ 6,132,122
Investments in associates and joint ventures	₩ 8,130,000	₩ 6,132,122	5,624,493
SK MENA Investment B.V. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Netherlands
Associates, Ownership (%)	32.10%	32.10%
Associates, Carrying amount	₩ 13,853	₩ 15,451
Investments in associates and joint ventures	₩ 13,853	₩ 15,451	14,929
SKY Property Mgmt. Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Virgin Island
Associates, Ownership (%)		33.00%
Associates, Carrying amount		₩ 263,225
Investments in associates and joint ventures		₩ 263,225	251,166
S.M. Culture & Contents Co., Ltd [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	Korea
Associates, Ownership (%)	23.40%
Associates, Carrying amount	₩ 64,966
Investments in associates and joint ventures	₩ 64,966
Xian Tianlong Science and Technology Co., Ltd. [Member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	China
Associates, Ownership (%)	49.00%	49.00%
Associates, Carrying amount	₩ 25,891	₩ 25,880
Investments in associates and joint ventures	₩ 25,891	25,880
Daehan Kanggun BcN Co., Ltd. and others [member]
Disclosure of investments in associates and joint ventures [Line Items]
Associates, Country	-
Associates, Carrying amount	₩ 96,479	115,181
Investments in associates and joint ventures	₩ 96,479	₩ 115,181	₩ 161,058

XML

Investments in Associates and Joint Ventures - Investments in Associates and Joint Ventures Accounted for using the Equity Method (Parenthetical) (Detail) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩) ₩ / shares shares	Dec. 31, 2017 USD ($) shares
SK China Company Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Value of shares in right issue | $		$ 100,000,000
SK Industrial Development China Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Number of shares acquired pursuant to rights issue	2,107,037	2,107,037
HappyNarae Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Price per shares acquired | ₩ / shares	₩ 17,212
Number of shares acquired	40,000	40,000
SKY Property Mgmt. Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Number of shares acquired pursuant to rights issue	8,101,884	8,101,884
S.M. Culture & Contents Co., Ltd [member]
Disclosure of investments in associates and joint ventures [Line Items]
Number of shares acquired	22,033,898	22,033,898
Number of shares acquired, purchase price | ₩	₩ 65,341

XML

Investments in Associates and Joint Ventures - Market Price of Investments in Listed Associates (Detail) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
NanoEnTek, Inc. [member]
Disclosure of associates [Line Items]
Market value per share	₩ 5,950	₩ 5,020
Number of shares	6,960,445	6,960,445
Fair value	₩ 41,415	₩ 34,941
SK hynix Inc. [member]
Disclosure of associates [Line Items]
Market value per share	₩ 76,500	₩ 44,700
Number of shares	146,100,000	146,100,000
Fair value	₩ 11,176,650	₩ 6,530,670
S.M. Culture & Contents Co., Ltd [member]
Disclosure of associates [Line Items]
Market value per share	₩ 2,700
Number of shares	22,033,898
Fair value	₩ 59,492

XML

Investments in Associates and Joint Ventures - Financial Information of Significant Associates (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of associates [Line Items]
Current assets	₩ 6,201,799	₩ 5,996,628
Non-current assets	27,226,870	25,301,035
Current liabilities	7,109,123	6,444,099
Non-current liabilities	8,290,351	8,737,134
Revenue	17,552,010	17,158,364	₩ 17,167,669
Profit for the year	2,657,595	1,660,101	1,515,885
Other comprehensive income (loss)	(1,013)	(247,331)	1,835
Total comprehensive income	2,656,582	1,412,770	1,517,720
SK hynix Inc. [member]
Disclosure of associates [Line Items]
Current assets	17,310,444	9,838,982
Non-current assets	28,108,020	22,377,044
Current liabilities	8,116,133	4,160,849
Non-current liabilities	3,481,412	4,031,647
Revenue	30,109,434	17,197,975	18,797,998
Profit for the year	10,642,219	2,960,483	4,323,595
Other comprehensive income (loss)	(422,042)	28,844	40,215
Total comprehensive income	10,220,177	2,989,327	4,363,810
KEB HanaCard Co., Ltd. [member]
Disclosure of associates [Line Items]
Current assets	7,339,492	6,868,387
Non-current assets	220,258	239,758
Current liabilities	1,181,746	1,219,327
Non-current liabilities	4,861,842	4,476,979
Revenue	1,519,607	1,413,077	1,472,830
Profit for the year	106,352	75,595	10,119
Other comprehensive income (loss)	(984)	(154)	(547)
Total comprehensive income	105,368	₩ 75,441	₩ 9,572
SK China Company Ltd. [member]
Disclosure of associates [Line Items]
Current assets	729,872
Non-current assets	1,031,647
Current liabilities	81,161
Non-current liabilities	64,717
Revenue	69,420
Profit for the year	11,492
Other comprehensive income (loss)	27,190
Total comprehensive income	₩ 38,682

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Investments in Associates and Joint Ventures - Condensed Financial Information of Joint Ventures (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of joint ventures [line items]
Current assets	₩ 6,201,799	₩ 5,996,628
Cash and cash equivalents	1,457,735	1,505,242	₩ 768,922	₩ 834,429
Non-current assets	27,226,870	25,301,035
Current liabilities	7,109,123	6,444,099
Non-current liabilities	8,290,351	8,737,134
Revenue	17,552,010	17,158,364	17,167,669
Depreciation and amortization	(3,097,466)	(2,941,886)	(2,845,295)
Interest income	366,561	575,050	103,900
Interest expense	(299,100)	(290,454)	(297,662)
Income tax benefit	(745,654)	(436,038)	(519,480)
Loss for the year	2,657,595	1,660,101	1,515,885
Total comprehensive income (loss)	2,656,582	1,412,770	1,517,720
Dogus Planet, Inc. [member]
Disclosure of joint ventures [line items]
Current assets	39,656	46,433
Cash and cash equivalents	25,818	45,839
Non-current assets	21,159	20,218
Current liabilities	32,622	26,417
Accounts payable, other payables and provision	2,743	1,971
Non-current liabilities	212	72
Revenue	82,791	53,864	38,944
Depreciation and amortization	(6,152)	(5,299)	(5,318)
Interest income	781	394	465
Interest expense	(4)	(2,139)
Loss for the year	(4,535)	(22,017)	(32,713)
Total comprehensive income (loss)	(4,535)	(22,017)	(32,713)
PT. Melon Indonesia [Member]
Disclosure of joint ventures [line items]
Revenue			17,094
Depreciation and amortization			(132)
Interest income			288
Loss for the year			1,853
Total comprehensive income (loss)			1,853
PT XL planet digital [member]
Disclosure of joint ventures [line items]
Current assets		20,077
Cash and cash equivalents		14,985
Non-current assets		50,765
Current liabilities		14,513
Accounts payable, other payables and provision		10,306
Non-current liabilities		1,305
Revenue		9,492	5,536
Depreciation and amortization		(940)	(2,746)
Interest income		267	525
Income tax benefit		51	7,025
Loss for the year		(49,438)	(21,381)
Total comprehensive income (loss)		(49,438)	₩ (21,381)
Finnq Co. Ltd. [member]
Disclosure of joint ventures [line items]
Current assets	32,232	48,699
Cash and cash equivalents	4,590	48,408
Non-current assets	15,610	673
Current liabilities	5,685	138
Accounts payable, other payables and provision	2,290	15
Non-current liabilities	13,862	784
Depreciation and amortization	(1,077)	(12)
Interest income	532	182
Interest expense	(276)
Loss for the year	(15,699)	(829)
Total comprehensive income (loss)	₩ (15,699)	₩ (829)

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Investments in Associates and Joint Ventures - Reconciliations of Financial Information of Significant Associates to Carrying Amounts of Investments in Associates in the Consolidated Financial Statements (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of associates [Line Items]
Carrying amount	₩ 9,498,381	₩ 7,306,816
SK hynix Inc. [member]
Disclosure of associates [Line Items]
Net assets	₩ 33,814,467	₩ 24,016,955
Ownership interests (%)	20.10%	20.10%
Net assets attributable to ownership interests	₩ 6,997,560	₩ 4,970,267
Cost-book value differentials	1,132,440	1,161,855
Carrying amount	8,130,000	6,132,122
KEB HanaCard Co., Ltd. [member]
Disclosure of associates [Line Items]
Net assets	₩ 1,516,162	₩ 1,411,839
Ownership interests (%)	15.00%	15.00%
Net assets attributable to ownership interests	₩ 227,424	₩ 211,776
Cost-book value differentials	53,564	54,022
Carrying amount	280,988	₩ 265,798
SK China Company Ltd. [member]
Disclosure of associates [Line Items]
Net assets	₩ 1,612,899
Ownership interests (%)	27.30%	9.60%
Net assets attributable to ownership interests	₩ 439,857
Cost-book value differentials	86,242
Carrying amount	₩ 526,099	₩ 46,354

XML

Investments in Associates and Joint Ventures - Reconciliations of Financial Information of Significant Associates to Carrying Amounts of Investments in Associates in the Consolidated Financial Statements (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
SK hynix Inc. [member]
Disclosure of associates [Line Items]
Equity method effective ownership interest	20.69%	20.69%

XML

Investments in Associates and Joint Ventures - Details of the Changes in Investments in Associates and Joint Ventures Accounted for using the Equity Method (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	₩ 7,404,323	₩ 6,896,293
Acquisition and disposition	161,824	67,048
Share of profit (loss)	2,164,427	536,759
Other comprehensive income (loss)	(140,748)	(9,991)
Impairment loss	(1,311)	(6,972)
Other increase (decrease)	(50,077)	(78,814)
Ending balance	9,538,438	7,404,323
SK China Company Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	46,354	43,814
Acquisition and disposition	113,803
Share of profit (loss)	2,707	2,257
Other comprehensive income (loss)	(36,783)	283
Other increase (decrease)	400,018
Ending balance	526,099	46,354
Korea IT fund [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	263,850	260,456
Share of profit (loss)	(8,815)	14,864
Other comprehensive income (loss)	3,371	(5,388)
Other increase (decrease)	(1,403)	(6,082)
Ending balance	257,003	263,850
KEB HanaCard Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	265,798	254,177
Share of profit (loss)	15,494	11,658
Other comprehensive income (loss)	(304)	(37)
Ending balance	280,988	265,798
NanoEnTek, Inc. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	39,514	45,008
Share of profit (loss)	(733)	(3,950)
Other comprehensive income (loss)	(63)	(1,544)
Ending balance	38,718	39,514
SK Industrial Development China Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	74,717	86,324
Share of profit (loss)	5,154	(6,298)
Other comprehensive income (loss)	(1,092)	(5,309)
Other increase (decrease)	(78,779)
Ending balance		74,717
SK Technology Innovation Company [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	47,488	45,891
Share of profit (loss)	433	162
Other comprehensive income (loss)	(5,410)	1,435
Ending balance	42,511	47,488
HappyNarae Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	17,236	17,095
Acquisition and disposition	688
Share of profit (loss)	3,929	240
Other comprehensive income (loss)	20	(99)
Ending balance	21,873	17,236
SK hynix Inc. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	6,132,122	5,624,493
Share of profit (loss)	2,175,887	572,086
Other comprehensive income (loss)	(90,349)	8,593
Other increase (decrease)	(87,660)	(73,050)
Ending balance	8,130,000	6,132,122
SK MENA Investment B.V. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	15,451	14,929
Share of profit (loss)	131	63
Other comprehensive income (loss)	(1,729)	459
Ending balance	13,853	15,451
SKY Property Mgmt. Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	263,225	251,166
Share of profit (loss)	2,362	16,066
Other comprehensive income (loss)	1,141	(4,007)
Other increase (decrease)	(266,728)
Ending balance		263,225
S.M. Culture & Contents Co., Ltd [member]
Disclosure of investments in associates and joint ventures [Line Items]
Acquisition and disposition	65,341
Share of profit (loss)	(375)
Ending balance	64,966
Xinan Tianlong Science and Technology Co., Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	25,880	25,767
Share of profit (loss)		113
Ending balance		25,880
Daehan Kanggun BcN Co., Ltd. and others [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	115,181	161,058
Acquisition and disposition	(1,306)	(26,798)
Share of profit (loss)	(6,924)	(13,179)
Other comprehensive income (loss)	(2,723)	754
Impairment loss	(1,311)	(6,972)
Other increase (decrease)	(6,438)	318
Ending balance	96,479	115,181
Associates [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	7,306,816	6,850,322
Acquisition and disposition	178,526	(45,658)
Share of profit (loss)	2,189,261	593,409
Other comprehensive income (loss)	(133,921)	(5,471)
Impairment loss	(1,311)	(6,972)
Other increase (decrease)	(40,990)	(78,814)
Ending balance	9,498,381	7,306,816
Candle Media Co., Ltd. [Member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance		20,144
Acquisition and disposition		(18,860)
Share of profit (loss)		(673)
Other comprehensive income (loss)		(611)
Xian Tianlong Science and Technology Co., Ltd. [Member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	25,880
Share of profit (loss)	11
Ending balance	25,891	25,880
PT XL planet digital [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	27,512	23,108
Acquisition and disposition	(18,864)	29,123
Share of profit (loss)	(8,648)	(24,719)
Ending balance		27,512
PT. Melon Indonesia [Member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance		4,339
Acquisition and disposition		(3,488)
Share of profit (loss)		918
Other comprehensive income (loss)		(1,769)
Dogus Planet, Inc. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	20,081	15,118
Acquisition and disposition	2,162	18,722
Share of profit (loss)	(2,267)	(11,008)
Other comprehensive income (loss)	(5,985)	(2,751)
Ending balance	13,991	20,081
Finnq Co. Ltd. [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	24,174
Acquisition and disposition		24,580
Share of profit (loss)	(7,691)	(406)
Other comprehensive income (loss)	(9)
Ending balance	16,474	24,174
Celcom Planet and others [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	25,740	3,406
Acquisition and disposition		43,769
Share of profit (loss)	(6,228)	(21,435)
Other comprehensive income (loss)	(833)
Other increase (decrease)	(9,087)
Ending balance	9,592	25,740
Joint ventures [member]
Disclosure of investments in associates and joint ventures [Line Items]
Beginning balance	97,507	45,971
Acquisition and disposition	(16,702)	112,706
Share of profit (loss)	(24,834)	(56,650)
Other comprehensive income (loss)	(6,827)	(4,520)
Other increase (decrease)	(9,087)
Ending balance	₩ 40,057	₩ 97,507

XML

Investments in Associates and Joint Ventures - Details of the Changes in Investments in Associates and Joint Ventures Accounted for using the Equity Method (Parenthetical) (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of investments in associates and joint ventures [Line Items]
Loss on disposal shares	₩ 36,024	₩ 2,919	₩ 2,599
Gain on disposal of shares	4,890	459,349	₩ 10,786
PT XL planet digital [member]
Disclosure of investments in associates and joint ventures [Line Items]
Loss on disposal shares	₩ 27,900
PT. Melon Indonesia [Member]
Disclosure of investments in associates and joint ventures [Line Items]
Gain on disposal of shares		₩ 11,634

XML

Investments in Associates and Joint Ventures - Details of Cumulative Unrecognized Equity Method Losses (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)
Disclosure of associates [Line Items]
Unrecognized loss (profit)	₩ (6,665)
Unrecognized loss (profit), cumulative loss	7,416
Unrecognized change in equity	0
Unrecognized change in equity, cumulative loss	365
Wave City Development Co., Ltd. [member]
Disclosure of associates [Line Items]
Unrecognized loss (profit)	(1,190)
Unrecognized loss (profit), cumulative loss	2,100
Unrecognized change in equity	0
Daehan Kanggun BcN Co., Ltd. and others [member]
Disclosure of associates [Line Items]
Unrecognized loss (profit)	(5,475)
Unrecognized loss (profit), cumulative loss	5,316
Unrecognized change in equity	0
Unrecognized change in equity, cumulative loss	₩ 365

XML

Property and Equipment - Summary of Property and Equipment (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	₩ 10,144,882	₩ 10,374,212	₩ 10,371,256
Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	35,844,640	35,339,956
Accumulated depreciation and amortization [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(25,696,088)	(24,963,296)
Accumulated impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(3,670)	(2,448)
Land [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	862,861	835,909	812,947
Land [member] | Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	862,861	835,909
Buildings and structures [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	882,650	899,972	911,129
Buildings and structures [member] | Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	1,638,749	1,604,863
Buildings and structures [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(756,099)	(704,891)
Structures [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	378,575	358,955	344,221
Structures [member] | Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	866,909	812,010
Structures [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(488,334)	(453,055)
Machinery [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	7,079,798	7,036,050	7,342,009
Machinery [member] | Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	30,343,739	29,705,088
Machinery [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(23,262,762)	(22,667,047)
Machinery [member] | Accumulated impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(1,179)	(1,991)
Other property and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	531,057	563,034	473,438
Other property and equipment [member] | Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	1,722,441	1,701,794
Other property and equipment [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(1,188,893)	(1,138,303)
Other property and equipment [member] | Accumulated impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	(2,491)	(457)
Construction in progress [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	409,941	680,292	₩ 487,512
Construction in progress [member] | Gross amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment	₩ 409,941	₩ 680,292

XML

Property and Equipment - Changes in Property and Equipment (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	₩ 10,374,212	₩ 10,371,256
Acquisition	2,759,356	2,663,003
Disposal	(60,116)	(74,157)
Transfer	(480,611)	(202,774)
Depreciation	(2,444,648)	(2,380,133)
Impairment	(3,012)	(2,983)
Business Combination	315
Other	(614)
Ending balance	10,144,882	10,374,212
Land [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	835,909	812,947
Acquisition	13,093	2,464
Disposal	(4,449)	(3,514)
Transfer	18,308	24,012
Ending balance	862,861	835,909
Buildings and structures [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	899,972	911,129
Acquisition	5,098	4,637
Disposal	(477)	(9,176)
Transfer	29,614	43,910
Depreciation	(51,557)	(50,528)
Ending balance	882,650	899,972
Structures [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	358,955	344,221
Acquisition	46,614	33,802
Disposal	(74)	(33)
Transfer	8,386	15,145
Depreciation	(35,306)	(34,180)
Ending balance	378,575	358,955
Machinery [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	7,036,050	7,342,009
Acquisition	656,731	660,629
Disposal	(41,692)	(45,672)
Transfer	1,644,045	1,234,737
Depreciation	(2,214,524)	(2,152,725)
Impairment	(778)	(2,928)
Other	(34)
Ending balance	7,079,798	7,036,050
Other property and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	563,034	473,438
Acquisition	720,431	807,047
Disposal	(9,252)	(6,052)
Transfer	(597,404)	(568,644)
Depreciation	(143,261)	(142,700)
Impairment	(2,234)	(55)
Business Combination	315
Other	(572)
Ending balance	531,057	563,034
Construction in progress [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	680,292	487,512
Acquisition	1,317,389	1,154,424
Disposal	(4,172)	(9,710)
Transfer	(1,583,560)	(951,934)
Other	(8)
Ending balance	₩ 409,941	₩ 680,292

XML

Investment Property - Additional Information (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about investment property [abstract]
Investment property	₩ 0	₩ 0	₩ 15,071

XML

Investment Property - Changes in Investment Properties (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2016 KRW (₩)
Disclosure of detailed information about investment property [line items]
Beginning balance	₩ 15,071
Reclassification	(14,968)
Depreciation	(103)
Ending balance	0
Land [member]
Disclosure of detailed information about investment property [line items]
Beginning balance	10,634
Reclassification	(10,634)
Buildings and structures [member]
Disclosure of detailed information about investment property [line items]
Beginning balance	4,437
Reclassification	(4,334)
Depreciation	₩ (103)

XML

Investment Property - Income and Expenses from Investment Property (Detail) - KRW (₩) ₩ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about investment property [abstract]
Rent revenue	₩ 386	₩ 850
Operating expense	₩ (114)	₩ (240)

XML

Goodwill - Summary of Goodwill (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	₩ 1,915,017	₩ 1,932,452	₩ 1,908,590
Shinsegi Telecom, Inc. [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	1,306,236	1,306,236
SK Broadband Co., Ltd. [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	358,443	358,443
Other acquisitions [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	₩ 250,338	₩ 267,773

XML

Goodwill - Additional Information (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	₩ 1,915,017	₩ 1,932,452	₩ 1,908,590
Accumulated impairment [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	₩ 50,710	17,269
Shinsegi Telecom, Inc. [member]
Disclosure of reconciliation of changes in goodwill [line items]
Annual discount rate	6.60%
Annual growth rate	0.40%
Goodwill	₩ 1,306,236	1,306,236
SK Broadband Co., Ltd. [member]
Disclosure of reconciliation of changes in goodwill [line items]
Annual discount rate	5.10%
Annual growth rate	1.00%
Goodwill	₩ 358,443	₩ 358,443

XML

Goodwill - Details of the Changes in Goodwill (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reconciliation of changes in goodwill [abstract]
Beginning balance	₩ 1,932,452	₩ 1,908,590
Acquisition	35,221	19,974
Impairment loss	(33,441)
Other	(19,215)	3,888
Ending balance	₩ 1,915,017	₩ 1,932,452

XML

Intangible Assets - Summary of Intangible Assets (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about intangible assets [line items]
Intangible assets	₩ 3,586,965	₩ 3,776,354	₩ 2,304,784
Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	9,410,703	8,812,457
Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(5,773,902)	(4,993,784)
Accumulated impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(49,836)	(42,319)
Frequency usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	2,176,940	2,580,828	1,103,517
Frequency usage rights [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	4,843,955	4,843,955
Frequency usage rights [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(2,667,015)	(2,263,127)
Land usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	15,750	20,834	26,576
Land usage rights [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	65,841	65,148
Land usage rights [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(50,091)	(44,314)
Industrial rights [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	111,347	121,200	116,542
Industrial rights [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	166,082	160,897
Industrial rights [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(54,735)	(39,697)
Development costs [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	4,103	4,871	7,472
Development costs [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	140,460	141,727
Development costs [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(134,828)	(136,446)
Development costs [member] | Accumulated impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(1,529)	(410)
Facility usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	36,451	41,788	48,019
Facility usage rights [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	153,438	151,906
Facility usage rights [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(116,987)	(110,118)
Customer relations [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	4,035	6,652	7,175
Customer relations [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	20,796	19,742
Customer relations [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(16,761)	(13,090)
Club memberships [Member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	73,614	74,039	91,507
Club memberships [Member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	108,382	113,161
Club memberships [Member] | Accumulated impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(34,768)	(39,122)
Other [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	1,164,725	926,142	₩ 903,976
Other [member] | Gross amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	3,911,749	3,315,921
Other [member] | Accumulated depreciation and amortization [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	(2,733,485)	(2,386,992)
Other [member] | Accumulated impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets	₩ (13,539)	₩ (2,787)

XML

Intangible Assets - Details of the Changes in Intangible Assets (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about intangible assets [line items]
Beginning balance	₩ 3,776,354	₩ 2,304,784
Acquisition	146,457	1,974,752
Disposal	(24,195)	30,049
Transfer	497,300	233,683
Amortiza- tion	(802,871)	(688,322)
Impairment	(18,493)	(21,523)
Business combina- tion	14,122	3,029
Others	(1,709)
Ending balance	3,586,965	3,776,354
Frequency usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	2,580,828	1,103,517
Acquisition		1,810,076
Amortiza- tion	(403,888)	(332,765)
Ending balance	2,176,940	2,580,828
Land usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	20,834	26,576
Acquisition	3,689	5,338
Disposal	(972)	1,921
Transfer	200
Amortiza- tion	(8,001)	(9,159)
Ending balance	15,750	20,834
Industrial rights [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	121,200	116,542
Acquisition	2,677	6,226
Disposal	(28)	148
Transfer	(5,635)	5,004
Amortiza- tion	(6,870)	(6,424)
Business combina- tion	4
Others	(1)
Ending balance	111,347	121,200
Development costs [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	4,871	7,472
Acquisition	3,813	1,404
Disposal	(9)
Transfer	(793)	338
Amortiza- tion	(2,660)	(3,933)
Impairment	(1,119)	(410)
Ending balance	4,103	4,871
Facility usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	41,788	48,019
Acquisition	2,805	2,181
Disposal	(36)	50
Transfer	129	231
Amortiza- tion	(8,235)	(8,593)
Ending balance	36,451	41,788
Customer relations [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	6,652	7,175
Acquisition	1,054	499
Amortiza- tion	(3,671)	(4,051)
Business combina- tion		3,029
Ending balance	4,035	6,652
Club memberships [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	74,039	91,507
Acquisition	5,023	7,983
Disposal	(3,452)	7,624
Transfer	122
Impairment	(769)	(17,827)
Others	(1,349)
Ending balance	73,614	74,039
Other [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	926,142	903,976
Acquisition	127,396	141,045
Disposal	(19,698)	20,306
Transfer	503,277	228,110
Amortiza- tion	(369,546)	(323,397)
Impairment	(16,605)	(3,286)
Business combina- tion	14,118
Others	(359)
Ending balance	₩ 1,164,725	₩ 926,142

XML

Intangible Assets - Details of the Changes in Intangible Assets (Parenthetical) (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about intangible assets [line items]
Impairment loss	₩ 18,493	₩ 21,523
2.6GHz license [Member]
Disclosure of detailed information about intangible assets [line items]
Purchase price of frequency rights		₩ 1,330,100
Remaining consideration payment period		10 years
2.1GHz license [Member]
Disclosure of detailed information about intangible assets [line items]
Purchase price of frequency rights		₩ 568,500
Remaining consideration payment period		5 years

XML

Intangible Assets - Research and Development Expenditures Recognized as Expense (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about intangible assets [abstract]
Research and development costs expensed as incurred	₩ 395,276	₩ 344,787	₩ 315,790

XML

Intangible Assets - Carrying Amount and Residual Useful Lives of Frequency Usage Rights (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 3,586,965	₩ 3,776,354	₩ 2,304,784
800MHz license [Member]
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 141,904
Description	Frequency usage rights relating to CDMA and LTE service
Commencement of amortization	2011-07
Completion of amortization	2021-01
1.8GHz license [Member]
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 502,480
Description	Frequency usage rights relating to LTE service
Commencement of amortization	2013-09
Completion of amortization	2021-12
WiBro service for 2.3GHz band [Member]
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 2,957
Description	WiBro service
Commencement of amortization	2012-03
Completion of amortization	2019-03
2.6GHz license [Member]
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 1,092,770
Description	Frequency usage rights relating to LTE service
Commencement of amortization	2016-09
Completion of amortization	2026-12
2.1GHz license [Member]
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 436,829
Description	Frequency usage rights relating to W-CDMA and LTE service
Commencement of amortization	2016-12
Completion of amortization	2021-12
Frequency usage rights [member]
Disclosure of detailed information about intangible assets [line items]
Amount	₩ 2,176,940	₩ 2,580,828	₩ 1,103,517

XML

Borrowings and Debentures - Short-term Borrowings (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about borrowings [line items]
Short-term borrowings	₩ 130,000	₩ 2,614
Shortterm Borrowings From Shinhan Bank [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate	2.85%
Short-term borrowings	₩ 30,000
Short-term borrowings from Woori Bank [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate	2.88%
Short-term borrowings		₩ 2,614
Commercial Paper From KEB Hana Bank [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate	1.67%
Short-term borrowings	₩ 50,000
Bank Overdraft From KEB Hana Bank [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate	3.17%
Short-term borrowings	₩ 30,000
Bank overdraft From Shinhan Bank [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate	3.38%
Short-term borrowings	₩ 20,000

XML

Borrowings and Debentures - Long-term Borrowings (Detail) $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 KRW (₩)	Dec. 31, 2016 USD ($)
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	₩ 252,817		₩ 172,907
Less current installments	(41,331)		(33,191)
Long-term borrowings, excluding current installments	211,486		139,716
Gross amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	₩ 253,771		174,493
Gross amount [member] | Korea Development Bank Longterm Borrowings with 3.20 Percent Interest Due March 31 2020 [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	3.20%	3.20%
Maturity	Mar. 31, 2020
Long-term borrowings	₩ 30,000
Gross amount [member] | KEB Hana bank longterm borrowings with3.18 percent interest due February 28 2019 [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	3.18%	3.18%
Maturity	Feb. 28, 2019
Long-term borrowings	₩ 40,000
Gross amount [member] | Kookmin Bank long-term borrowings with 1.29% interest due March 15, 2017 [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	1.29%	1.29%
Maturity	Mar. 15, 2017
Long-term borrowings			500
Gross amount [member] | Kookmin Bank Longterm Borrowings With 1.95 Percent Interest Due March 15 2018 [member ]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	1.95%	1.95%
Maturity	Mar. 15, 2018
Long-term borrowings	₩ 717		3,583
Gross amount [member] | Korea Development Bank Longterm Borrowings With 1.99 Percent Interest Due Jul. 30, 2019 [member ]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	1.99%	1.99%
Maturity	Jul. 30, 2019
Long-term borrowings	₩ 22,750		35,750
Gross amount [member] | Korea Development Bank Longterm Borrowings With 1.99 Percent Interest Due Jul. 30, 2019 Two [member ]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	1.99%	1.99%
Maturity	Jul. 30, 2019
Long-term borrowings	₩ 5,833		9,167
Gross amount [member] | Korea Development Bank Longterm Borrowings With 2.27 Percent Interest Due Dec. 20, 2021 [member ]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	₩ 49,000		49,000
Gross amount [member] | Korea Development Bank Longterm Borrowings With 2.37 Percent Interest Due Dec. 21, 2022 [member ]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	2.37%	2.37%
Maturity	Dec. 21, 2022
Long-term borrowings	₩ 50,000
Gross amount [member] | Export Kreditnamnden long-term borrowings with 1.70% interest due April 29, 2022 [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	1.70%	1.70%
Maturity	Apr. 29, 2022
Long-term borrowings	₩ 55,471	$ 51,775	76,493	$ 63,296
Gross amount [member] | Korea Development Bank long-term borrowings with 2.32% interest due December 20, 2021 [Member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	2.27%	2.27%
Maturity	Dec. 20, 2021
Present value discount [Member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	₩ (954)		₩ (1,586)

XML

Borrowings and Debentures - Debentures (Detail) SFr in Thousands, $ in Thousands, $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 KRW (₩)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 AUD ($)	Dec. 31, 2016 CHF (SFr)
Disclosure of detailed information about borrowings [line items]
Debentures	₩ 7,086,187		₩ 7,194,206
Less current installments of bonds	(1,489,617)		(855,276)
Debentures, excluding current installments, net	5,596,570		6,338,930
Gross amount [member]
Disclosure of detailed information about borrowings [line items]
Debentures	₩ 7,107,216		7,220,064
Gross amount [member] | Unsecured private bonds with 5.00% interest due 2016 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2018
Annual interest rate (%)	5.00%	5.00%
Debentures	₩ 200,000		200,000
Gross amount [member] | Unsecured private bonds with 4.22% interest due 2021 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2021
Annual interest rate (%)	4.22%	4.22%
Debentures	₩ 190,000		190,000
Gross amount [member] | Unsecured private bonds with 3.24% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	3.24%	3.24%
Debentures	₩ 170,000		170,000
Gross amount [member] | Unsecured private bonds with 3.30% interest due 2022 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	3.30%	3.30%
Debentures	₩ 140,000		140,000
Gross amount [member] | Unsecured private bonds with 3.45% interest due 2032 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2032
Annual interest rate (%)	3.45%	3.45%
Debentures	₩ 90,000		90,000
Gross amount [member] | Unsecured private bonds with 3.03% interest due 2023 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2023
Annual interest rate (%)	3.03%	3.03%
Debentures	₩ 230,000		230,000
Gross amount [member] | Unsecured private bonds with 3.22% interest due 2033 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2033
Annual interest rate (%)	3.22%	3.22%
Debentures	₩ 130,000		130,000
Gross amount [member] | Unsecured private bonds with 3.30% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	3.30%	3.30%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured private bonds with 3.64% interest due 2024 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2024
Annual interest rate (%)	3.64%	3.64%
Debentures	₩ 150,000		150,000
Gross amount [member] | Unsecured private bonds with 4.72% interest due 2029 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2029
Annual interest rate (%)	4.72%	4.72%
Debentures	₩ 60,278		59,600
Gross amount [member] | Unsecured private bonds with 2.53% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	2.53%	2.53%
Debentures	₩ 160,000		160,000
Gross amount [member] | Unsecured private bonds with 2.66% interest due 2021 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2021
Annual interest rate (%)	2.66%	2.66%
Debentures	₩ 150,000		150,000
Gross amount [member] | Unsecured private bonds with 2.82% interest due 2024 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2024
Annual interest rate (%)	2.82%	2.82%
Debentures	₩ 190,000		190,000
Gross amount [member] | Unsecured private bonds with 2.40% interest due 2022 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	2.40%	2.40%
Debentures	₩ 100,000		100,000
Gross amount [member] | Unsecured private bonds with 2.49% interest due 2025 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2025
Annual interest rate (%)	2.49%	2.49%
Debentures	₩ 150,000		150,000
Gross amount [member] | Unsecured private bonds with 2.61% interest due 2030 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2030
Annual interest rate (%)	2.61%	2.61%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured private bonds with 1.89% interest due 2018 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2018
Annual interest rate (%)	1.89%	1.89%
Debentures	₩ 90,000		90,000
Gross amount [member] | Unsecured private bonds with 2.66% interest due 2025 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2025
Annual interest rate (%)	2.66%	2.66%
Debentures	₩ 70,000		70,000
Gross amount [member] | Unsecured private bonds with 2.82% interest due 2030 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2030
Annual interest rate (%)	2.82%	2.82%
Debentures	₩ 90,000		90,000
Gross amount [member] | Unsecured private bonds with 2.07% interest due 2018 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2018
Annual interest rate (%)	2.07%	2.07%
Debentures	₩ 80,000		80,000
Gross amount [member] | Unsecured private bonds with 2.55% interest due 2025 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2025
Annual interest rate (%)	2.55%	2.55%
Debentures	₩ 100,000		100,000
Gross amount [member] | Unsecured private bonds with 2.75% interest due 2035 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2035
Annual interest rate (%)	2.75%	2.75%
Debentures	₩ 70,000		70,000
Gross amount [member] | Unsecured private bonds with 1.65% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	1.65%	1.65%
Debentures	₩ 70,000		70,000
Gross amount [member] | Unsecured private bonds with 1.80% interest due 2021 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2021
Annual interest rate (%)	1.80%	1.80%
Debentures	₩ 100,000		100,000
Gross amount [member] | Unsecured private bonds with 2.08% interest due 2026 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2026
Annual interest rate (%)	2.08%	2.08%
Debentures	₩ 90,000		90,000
Gross amount [member] | Unsecured private bonds with 2.24% interest due 2036 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2036
Annual interest rate (%)	2.24%	2.24%
Debentures	₩ 80,000		80,000
Gross amount [member] | Unsecured private bonds with 1.62% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	1.62%	1.62%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured private bonds with 1.71% interest due 2021 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2021
Annual interest rate (%)	1.71%	1.71%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured private bonds with 1.97% interest due 2026 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2026
Annual interest rate (%)	1.97%	1.97%
Debentures	₩ 120,000		120,000
Gross amount [member] | Unsecured private bonds with 2.17% interest due 2031 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2031
Annual interest rate (%)	2.17%	2.17%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured corporate bonds with 1.93% interest due 2020 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2020
Annual interest rate (%)	1.93%	1.93%
Debentures	₩ 60,000
Gross amount [member] | Unsecured corporate bonds with 2.17% interest due 2022.[member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	2.17%	2.17%
Debentures	₩ 120,000
Gross amount [member] | Unsecured corporate bonds with 2.55% interest due 2027 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2027
Annual interest rate (%)	2.55%	2.55%
Debentures	₩ 100,000
Gross amount [member] | Unsecured corporate bonds with 2.65% interest due 2032 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2032
Annual interest rate (%)	2.65%	2.65%
Debentures	₩ 90,000
Gross amount [member] | Unsecured corporate bonds with 2.39% interest due 2020 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2020
Annual interest rate (%)	2.39%	2.39%
Debentures	₩ 100,000
Gross amount [member] | Unsecured corporate bonds with 2.63% interest due 2022 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	2.63%	2.63%
Debentures	₩ 80,000
Gross amount [member] | Unsecured private bonds with 4.28% interest due 2017 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2017
Annual interest rate (%)	4.28%	4.28%
Debentures	₩ 100,000
Gross amount [member] | Unsecured private bonds with 3.27% interest due 2017 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2017
Annual interest rate (%)	3.27%	3.27%
Debentures			100,000
Gross amount [member] | Unsecured private bonds with 3.05% interest due 2016 [Member]
Disclosure of detailed information about borrowings [line items]
Debentures			120,000
Gross amount [member] | Unsecured private bonds with 3.49% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	3.49%	3.49%
Debentures	₩ 210,000		210,000
Gross amount [member] | Unsecured private bonds with 2.76% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	2.76%	2.76%
Debentures	₩ 130,000		130,000
Gross amount [member] | Unsecured private bonds with 2.23% interest due 2018 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2018
Annual interest rate (%)	2.23%	2.23%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured private bonds with 2.49% interest due 2020 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2020
Annual interest rate (%)	2.49%	2.49%
Debentures	₩ 160,000		160,000
Gross amount [member] | Unsecured private bonds with 2.43% interest due 2020 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2020
Annual interest rate (%)	2.43%	2.43%
Debentures	₩ 140,000		140,000
Gross amount [member] | Unsecured private bonds with 2.18% interest due 2020 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2020
Annual interest rate (%)	2.18%	2.18%
Debentures	₩ 130,000		130,000
Gross amount [member] | Unsecured private bonds with 1.58% interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	1.58%	1.58%
Debentures	₩ 50,000		50,000
Gross amount [member] | Unsecured private bonds with 1.77% interest due 2021 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2021
Annual interest rate (%)	1.77%	1.77%
Debentures	₩ 120,000		120,000
Gross amount [member] | Unsecured private bonds with 3.24% interest due 2016 [member]
Disclosure of detailed information about borrowings [line items]
Debentures	₩ 150,000
Gross amount [member] | Unsecured private bonds with 3.48% interest due 2017 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2017
Annual interest rate (%)	3.48%	3.48%
Debentures	₩ 30,000		20,000
Gross amount [member] | Unsecured corporate bonds with 2.70% interest due 2022 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	2.70%	2.70%
Debentures	₩ 140,000
Gross amount [member] | Corporate bonds with 1.00 percent interest due 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2019
Annual interest rate (%)	1.00%	1.00%
Debentures	₩ 5,558
Gross amount [member] | Unsecured global bonds with 6.63% interest due 2027 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2027
Annual interest rate (%)	6.63%	6.63%
Debentures	₩ 428,560	$ 400,000	483,400	$ 400,000
Gross amount [member] | Unsecured private Swiss bonds with 1.75% interest due 2017 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2017
Annual interest rate (%)	1.75%	1.75%
Debentures			354,399			SFr 300,000
Gross amount [member] | Unsecured global bonds with 2.13% interest due 2018 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2018
Annual interest rate (%)	2.13%	2.13%
Debentures	₩ 749,980	$ 700,000	845,950	700,000
Gross amount [member] | Unsecured private Australian bonds with 4.75% interest due 2017 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2017
Annual interest rate (%)	4.75%	4.75%
Debentures			261,615		$ 300,000
Gross amount [member] | Floating rate notes with 3M Libor + 0.88% interest due 2020 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2020
Annual interest rate description	3M Libor +
Annual interest rate adjustment (%)	0.88%	0.88%
Debentures	₩ 321,420	$ 300,000	362,550	300,000
Gross amount [member] | Foreign global bonds with 2.88% interest due 2018 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2018
Annual interest rate (%)	2.88%	2.88%
Debentures	₩ 321,420	$ 300,000	362,550	$ 300,000
Gross amount [member] | Unsecured corporate bonds with 2 point 84 percent interest due 2027 [member]
Disclosure of detailed information about borrowings [line items]
Maturity	2027
Annual interest rate (%)	2.84%	2.84%
Gross amount [member] | Unsecured corporate bonds with 2.26% interest due 2022 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	2.26%	2.26%
Gross amount [member] | Unsecured corporate bonds with 2.34% interest due 2022 [Member]
Disclosure of detailed information about borrowings [line items]
Maturity	2022
Annual interest rate (%)	2.34%	2.34%
Discounts on bonds [Member]
Disclosure of detailed information about borrowings [line items]
Debentures	₩ (21,029)		₩ (25,858)

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Borrowings and Debentures - Debentures (Parenthetical) (Detail) ₩ in Millions	Dec. 31, 2017 KRW (₩)
Disclosure of detailed information about borrowings [line items]
Excess carrying amount of financial liabilities designated at fair value through profit or loss over the principal amount	₩ 10,278
3M LIBOR [Member]
Disclosure of detailed information about borrowings [line items]
Annual interest rate (%)	1.69%

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Long-term Payables Other - Summary of Long-term Payables - Other (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trade and other non-current payables [abstract]
Payables related to acquisition of frequency usage rights	₩ 1,328,630	₩ 1,602,943
Other	18,133	21,647
Other non current payables	₩ 1,346,763	₩ 1,624,590

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Long-term Payables Other - Details of Long-term Payables - Other, Which Consist of Payables Related to the Acquisition of Frequency Usage Rights (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial liabilities [line items]
Long-term payables - other	₩ 1,630,381	₩ 1,904,716
Less current installments of long-term payables - other	(301,751)	(301,773)
Carrying amount at December 31	1,328,630	1,602,943
Gross amount [member]
Disclosure of financial liabilities [line items]
Long-term payables - other	1,710,255	2,013,122
Present value discount [Member]
Disclosure of financial liabilities [line items]
Long-term payables - other	₩ (79,874)	₩ (108,406)

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Long-term Payables Other - Repayment Schedule of the Principal Amount of Long-term Payables - Other Related to Acquisition of Frequency Usage Rights (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial liabilities [line items]
Payables related to acquisition of frequency usage rights	₩ 1,630,381	₩ 1,904,716
Gross amount [member]
Disclosure of financial liabilities [line items]
Payables related to acquisition of frequency usage rights	1,710,255	₩ 2,013,122
Gross amount [member] | Less than 1 year [Member]
Disclosure of financial liabilities [line items]
Payables related to acquisition of frequency usage rights	302,867
Gross amount [member] | 1 - 3 years [Member]
Disclosure of financial liabilities [line items]
Payables related to acquisition of frequency usage rights	605,734
Gross amount [member] | 3 - 5 years [Member]
Disclosure of financial liabilities [line items]
Payables related to acquisition of frequency usage rights	402,624
Gross amount [member] | More than 5 years [member]
Disclosure of financial liabilities [line items]
Payables related to acquisition of frequency usage rights	₩ 399,030

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Provisions - Changes in Provisions (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of other provisions [line items]
Beginning balance	₩ 97,917	₩ 70,205
Increase	17,683	48,924
Utilization	(15,690)	(20,342)
Reversal	(15,229)	(913)
Other	45	43
Ending balance	84,726	97,917
Current	52,057	66,227
Non-current	32,669	31,690
Provision for installment of handset subsidy [Member]
Disclosure of other provisions [line items]
Beginning balance	24,710	5,670
Increase	2	37,530
Utilization	(8,898)	(18,490)
Reversal	(11,940)
Ending balance	3,874	24,710
Current	3,874	19,939
Non-current		4,771
Provision for restoration [Member]
Disclosure of other provisions [line items]
Beginning balance	64,679	59,954
Increase	12,066	6,677
Utilization	(2,517)	(1,082)
Reversal	(1,006)	(913)
Other	45	43
Ending balance	73,267	64,679
Current	40,598	37,760
Non-current	32,669	26,919
Emission allowance [Member]
Disclosure of other provisions [line items]
Beginning balance	2,788	1,477
Increase	4,663	1,480
Utilization	(518)	(169)
Reversal	(2,283)
Ending balance	4,650	2,788
Current	4,650	2,788
Other provisions [Member]
Disclosure of other provisions [line items]
Beginning balance	5,740	3,104
Increase	952	3,237
Utilization	(3,757)	(601)
Ending balance	2,935	5,740
Current	₩ 2,935	₩ 5,740

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Lease - Expected Future Lease Payments and Lease Revenues (Detail) ₩ in Millions	Dec. 31, 2017 KRW (₩)
Disclosure of detailed information about arrangements involving legal form of lease [line items]
Minimum lease payments	₩ 151,161
Revenues	2,842
Less than 1 year [Member]
Disclosure of detailed information about arrangements involving legal form of lease [line items]
Minimum lease payments	49,289
Revenues	1,926
1-5 years [member]
Disclosure of detailed information about arrangements involving legal form of lease [line items]
Minimum lease payments	101,872
Revenues	₩ 916

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Defined Benefit Liabilities (Assets) - Details of Defined Benefit Liabilities (Assets) (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [abstract]
Present value of defined benefit obligations	₩ 679,625	₩ 595,667
Fair value of plan assets	(663,617)	(555,175)
Defined benefit assets	(45,952)	(30,247)
Defined benefit liabilities	₩ 61,960	₩ 70,739

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Defined Benefit Liabilities (Assets) - Principal Actuarial Assumptions (Detail)	Dec. 31, 2017	Dec. 31, 2016
Bottom of range [member]
Disclosure of defined benefit plans [line items]
Discount rate for defined benefit obligations	2.58%	1.90%
Expected rate of salary increase	3.08%	2.49%
Top of range [member]
Disclosure of defined benefit plans [line items]
Discount rate for defined benefit obligations	4.03%	2.96%
Expected rate of salary increase	5.93%	6.09%

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Defined Benefit Liabilities (Assets) - Changes in Defined Benefit Obligations (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [line items]
Current service cost	₩ 125,526	₩ 114,528	₩ 106,764
Interest cost	2,170	3,615	3,257
Retirement benefit obligation [Member]
Disclosure of defined benefit plans [line items]
Beginning balance	595,667	525,269
Current service cost	125,526	114,528
Interest cost	15,991	13,441
Remeasurement
- Demographic assumption	(287)	677
- Financial assumption	(20,731)	(2,462)
- Adjustment based on experience	11,561	6,229
Benefit paid	(60,883)	(55,350)
Others	12,781	(6,665)
Ending balance	₩ 679,625	₩ 595,667	₩ 525,269

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Defined Benefit Liabilities (Assets) - Changes in Plan Assets (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of fair value of plan assets [line items]
Interest income	₩ (2,170)	₩ (3,615)	₩ (3,257)
Plan assets [member]
Disclosure of fair value of plan assets [line items]
Beginning balance	555,175	426,413
Interest income	13,821	9,826
Remeasurement	(5,540)	(6,320)
Contributions	155,834	159,687
Benefit paid	(60,006)	(34,247)
Others	4,333	(184)
Ending balance	₩ 663,617	₩ 555,175	₩ 426,413

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Defined Benefit Liabilities (Assets) - Additional Information (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩) yr
Disclosure of defined benefit plans [abstract]
Expected contributions in 2018 | ₩	₩ 146,086
Weighted average durations of defined benefit obligations | yr	8.17

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Defined Benefit Liabilities (Assets) - Total Amount of Expenses Recognized in Profit and Loss (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [abstract]
Current service cost	₩ 125,526	₩ 114,528	₩ 106,764
Net interest cost	2,170	3,615	3,257
Total amount of expenses recognized in profit and loss	₩ 127,696	₩ 118,143	₩ 110,021

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Defined Benefit Liabilities (Assets) - Details of Plan Assets (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [abstract]
Equity instruments	₩ 15,567	₩ 13,640
Debt instruments	134,710	95,359
Short-term financial instruments, etc.	513,340	446,176
Fair value of plan assets	₩ 663,617	₩ 555,175

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Defined Benefit Liabilities (Assets) - Effects on Defined Benefit Obligations if Each of Significant Actuarial Assumptions Changes Within Expectable and Reasonable Range (Detail) ₩ in Millions	Dec. 31, 2017 KRW (₩)
Discount rate [Member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in defined benefit obligations	₩ (24,702)
Increase in assumption	0.50%
Decrease in defined benefit obligations	₩ 26,808
Decrease in assumption	0.50%
Expected salary increase rate [Member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in defined benefit obligations	₩ 26,988
Increase in assumption	0.50%
Decrease in defined benefit obligations	₩ (25,138)
Decrease in assumption	0.50%

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Derivative Instruments - Currency and Interest Rate Swap Contracts under Cash Flow Hedge Accounting (Detail)	12 Months Ended
	Dec. 31, 2017
Fixed-to-fixed cross currency swap, Jul, 20, 2007 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Jul. 20, 2007
Hedging Instrument(Hedged item)	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 400,000)
Hedged risk	Foreign currency risk
Financial institution	Morgan Stanley and four other banks
Duration of contract	Jul. 20, 2007 ~ Jul. 20, 2027
Fixed-to-fixed Cross Currency Swap, Nov. 1, 2012 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Nov. 01, 2012
Hedging Instrument(Hedged item)	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 700,000)
Hedged risk	Foreign currency risk
Financial institution	Standard Chartered and eight other banks
Duration of contract	Nov. 1, 2012~ May. 1, 2018
Fixed-to-fixed Cross Currency Swap, Mar. 7, 2013 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Mar. 07, 2013
Hedging Instrument(Hedged item)	Floating-to-fixed cross currency interest rate swap (U.S. dollar denominated bonds face value of USD 300,000)
Hedged risk	Foreign currency risk and interest rate risk
Financial institution	DBS bank
Duration of contract	Mar. 7, 2013 ~ Mar. 7, 2020
Fixed-to-fixed Cross Currency Swap, Oct. 29, 2013 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Oct. 29, 2013
Hedging Instrument(Hedged item)	Fixed-to-fixed cross currency swap (U.S. dollar denominated bonds face value of USD 300,000)
Hedged risk	Foreign currency risk
Financial institution	Korea Development Bank and others
Duration of contract	Oct. 29, 2013 ~ Oct. 26, 2018
Fixed-to-fixed Cross Currency Swap, Dec. 16, 2013 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Dec. 16, 2013
Hedging Instrument(Hedged item)	Fixed-to-fixed cross currency swap (U.S. dollar borrowing amounting to USD 51,775)
Hedged risk	Foreign currency risk
Financial institution	Deutsche bank
Duration of contract	Dec. 16, 2013 ~ Apr. 29, 2022
Floating-to-fixed Interest Rate Swap, Dec. 20, 2016 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Dec. 20, 2016
Hedging Instrument(Hedged item)	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 49,000)
Hedged risk	Interest rate risk
Financial institution	Korea Development Bank
Duration of contract	Dec. 20, 2016~ Dec. 20, 2021
Floating-to-fixed Interest Rate Swap, Jan. 30, 2017 [Member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Jan. 30, 2017
Hedging Instrument(Hedged item)	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 28,583)
Hedged risk	Interest rate risk
Financial institution	Korea Development Bank
Duration of contract	Nov. 10, 2016~ Jul. 30, 2019
Floating-to-fixed Interest Rate Swap, Mar. 31, 2017 [member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Mar. 31, 2017
Hedging Instrument(Hedged item)	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 30,000)
Hedged risk	Interest rate risk
Financial institution	Korea Development Bank
Duration of contract	Mar. 31, 2017- Mar. 31, 2020
Floating-to-fixed interest rate swap, Dec. 21, 2017 [member]
Disclosure of detailed information about hedging instruments [line items]
Borrowing date	Dec. 21, 2017
Hedging Instrument(Hedged item)	Floating-to-fixed interest rate swap (Korean won borrowing amounting to KRW 50,000)
Hedged risk	Interest rate risk
Financial institution	Korea Development Bank
Duration of contract	Dec. 5, 2017- Dec. 21, 2022

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Derivative Instruments - Details of Fair Values of the Above Derivatives Recorded in Assets or Liabilities (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	₩ 253,213	₩ 214,770
Short-term derivative financial liabilities	(28,406)	(86,950)
Long-term derivative financial liabilities	(11,064)	(203)
Derivative financial liabilities	(39,470)	₩ (87,153)
Redeemable convertible preferred shares issued by Bluehole INC [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	222,257
Structured bonds [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	9,054
Fixed-to-fixed cross currency swap, Jul, 20, 2007 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	21,554
Floating-to-fixed Interest Rate Swap, Dec. 20, 2016 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	307
Floating-to-fixed Interest Rate Swap, Jan. 30, 2017 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	43
Floating-to-fixed interest rate swap, Dec. 21, 2017 [member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	(2)
Fixed-to-fixed Cross Currency Swap, Nov. 1, 2012 [Member]
Disclosure of detailed information about hedged items [line items]
Short-term derivative financial liabilities	(27,791)
Fixed-to-fixed Cross Currency Swap, Oct. 29, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Short-term derivative financial liabilities	(615)
Fixed-to-fixed Cross Currency Swap, Mar. 7, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial liabilities	(7,613)
Fixed-to-fixed Cross Currency Swap, Dec. 16, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial liabilities	(3,106)
Floating-to-fixed Interest Rate Swap, Mar. 31, 2017 [member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial liabilities	(345)
Valuation gain (loss) on derivatives [Member] | Fixed-to-fixed cross currency swap, Jul, 20, 2007 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	21,554
Valuation gain (loss) on derivatives [Member] | Floating-to-fixed Interest Rate Swap, Dec. 20, 2016 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	307
Valuation gain (loss) on derivatives [Member] | Floating-to-fixed Interest Rate Swap, Jan. 30, 2017 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	43
Valuation gain (loss) on derivatives [Member] | Floating-to-fixed interest rate swap, Dec. 21, 2017 [member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	(2)
Valuation gain (loss) on derivatives [Member] | Fixed-to-fixed Cross Currency Swap, Nov. 1, 2012 [Member]
Disclosure of detailed information about hedged items [line items]
Short-term derivative financial liabilities	(27,791)
Valuation gain (loss) on derivatives [Member] | Fixed-to-fixed Cross Currency Swap, Oct. 29, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Short-term derivative financial liabilities	(615)
Valuation gain (loss) on derivatives [Member] | Fixed-to-fixed Cross Currency Swap, Mar. 7, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial liabilities	(7,613)
Valuation gain (loss) on derivatives [Member] | Fixed-to-fixed Cross Currency Swap, Dec. 16, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial liabilities	(3,106)
Valuation gain (loss) on derivatives [Member] | Floating-to-fixed Interest Rate Swap, Mar. 31, 2017 [member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial liabilities	(345)
Held for trading [Member] | Structured bonds [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	9,054
Embedded derivatives [member] | Redeemable convertible preferred shares issued by Bluehole INC [Member]
Disclosure of detailed information about hedged items [line items]
Long-term derivative financial assets	₩ 222,257

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Derivative Instruments - Details of Fair Values of the Above Derivatives Recorded in Assets or Liabilities (Parenthetical) (Detail) - Dec. 31, 2017	KRW (₩)	USD ($)
Structured bonds [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | ₩	₩ 50,000,000,000
Fixed-to-fixed cross currency swap, Jul, 20, 2007 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | $		$ 400,000,000
Floating-to-fixed Interest Rate Swap, Dec. 20, 2016 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | ₩	49,000,000
Floating-to-fixed Interest Rate Swap, Jan. 30, 2017 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | ₩	28,583,000
Floating-to-fixed interest rate swap, Dec. 21, 2017 [member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | ₩	50,000,000
Fixed-to-fixed Cross Currency Swap, Nov. 1, 2012 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | $		700,000,000
Fixed-to-fixed Cross Currency Swap, Oct. 29, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | $		300,000,000
Fixed-to-fixed Cross Currency Swap, Mar. 7, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | $		300,000,000
Fixed-to-fixed Cross Currency Swap, Dec. 16, 2013 [Member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | $		$ 51,775,000
Floating-to-fixed Interest Rate Swap, Mar. 31, 2017 [member]
Disclosure of detailed information about hedged items [line items]
Bonds face value | ₩	₩ 30,000,000

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Share Capital and Capital Surplus (Deficit) and Others - Additional Information (Detail)	Dec. 31, 2017 ₩ / shares
Disclosure of classes of share capital [abstract]
Common stock, par value	₩ 500

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Share Capital and Capital Surplus (Deficit) and Others - Number of Authorized, Issued and Outstanding Common Shares and the Details of Capital Surplus (Deficit) and Others (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of classes of share capital [abstract]
Number of authorized shares	220,000,000	220,000,000
Number of issued shares	80,745,711	80,745,711	80,745,711
Share capital
Common share	₩ 44,639	₩ 44,639
Capital surplus (deficit) and others:
Paid-in surplus	2,915,887	2,915,887
Treasury shares(Note 24)	(2,260,626)	(2,260,626)
Share option(Note 26)	414
Others	(857,912)	(854,000)
Capital Surplus	₩ (202,237)	₩ (198,739)

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Share Capital and Capital Surplus (Deficit) and Others - Details of Shares Outstanding (Detail) - shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of number of shares outstanding [abstract]
Issued shares	80,745,711	80,745,711	80,745,711
Treasury shares	10,136,551	10,136,551
Outstanding shares	70,609,160	70,609,160

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Treasury Shares - Summary of Treasury Shares (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of classes of share capital [abstract]
Number of shares	10,136,551	10,136,551
Acquisition cost	₩ 2,260,626	₩ 2,260,626

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Hybrid Bonds - Summary of Hybrid Bonds (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Private hybrid bonds	₩ 398,518	₩ 398,518
Private hybrid bonds [Member]
Type	Unsecured subordinated bearer bond
Issuance date	Jun. 07, 2013
Maturity	June 7, 2073
Annual interest rate(%)	4.21%
Gross amount [member]
Private hybrid bonds	₩ 400,000
Issuance costs [Member]
Private hybrid bonds	₩ (1,482)

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Hybrid Bonds - Summary of Hybrid Bonds (Parenthetical) (Detail) - Private hybrid bonds [Member]	12 Months Ended
	Dec. 31, 2017
After 10 years [Member]
Annual interest rate, additional premium	0.25%
Annual interest rate, additional premium period	10 years
After 25 years [Member]
Annual interest rate, additional premium	0.75%
Annual interest rate, additional premium period	25 years

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Share Option - Summary of Terms and Conditions Related to Grants of Share Options under Share Option Program (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)
Series 1-1 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of shares	22,168
Exercise price	₩ 246,750
Exercise period	Mar. 25, 2019 ~ Mar. 24, 2022
Vesting conditions	2 years' service from the grant date
Series 1-2 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Grant date	March 24, 2017
Types of shares to be issued	66,504 of registered common shares
Grant method	Reissue of treasury shares sha
Number of shares	22,168
Exercise price	₩ 266,490
Exercise period	Mar. 25, 2020 ~ Mar. 24, 2023
Vesting conditions	3 years' service from the grant date
Series 1-3 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of shares	22,168
Exercise price	₩ 287,810
Exercise period	Mar. 25, 2021 ~ Mar. 24, 2024
Vesting conditions	4 years' service from the grant date

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Share Option - Summary of Share Compensation Expense Recognized (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)
Disclosure Of Share Based Compensation Expense [Line Items]
Share compensation expense	₩ 414
Major Share Options Transactions [Member]
Disclosure Of Share Based Compensation Expense [Line Items]
Share compensation expense	977
Events including and after reporting period [member]
Disclosure Of Share Based Compensation Expense [Line Items]
Share compensation expense	₩ 1,391

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Share Option - Summary of Inputs Used in Binomial Option Pricing Model (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩) yr
Series 1-1 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	1.86%
Estimated option's life | yr	5
Share price (Closing price on the preceding day in won)	₩ 262,500
Expected volatility	13.38%
Expected dividends	3.80%
Exercise price	₩ 246,750
Per share fair value of the option	₩ 27,015
Series 1-2 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	1.95%
Estimated option's life | yr	6
Share price (Closing price on the preceding day in won)	₩ 262,500
Expected volatility	13.38%
Expected dividends	3.80%
Exercise price	₩ 266,490
Per share fair value of the option	₩ 20,240
Series 1-3 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	2.07%
Estimated option's life | yr	7
Share price (Closing price on the preceding day in won)	₩ 262,500
Expected volatility	13.38%
Expected dividends	3.80%
Exercise price	₩ 287,810
Per share fair value of the option	₩ 15,480

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Retained Earnings - Summary of Retained Earnings (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reserves within equity [abstract]
Legal reserve	₩ 22,320	₩ 22,320
Reserve for research & manpower development		60,001
Reserve for business expansion	10,171,138	9,871,138
Reserve for technology development	3,071,300	2,826,300
Appropriated retained earnings	13,264,758	12,779,759
Unappropriated retained earnings	4,571,188	3,173,405
Retained earnings	₩ 17,835,946	₩ 15,953,164

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Retained Earnings - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure of reserves within equity [abstract]
Legal reserve as a percentage of cash dividends paid	10.00%
Legal reserve as a percentage of outstanding share capital	50.00%

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Reserves - Details of Reserves, Net of Taxes (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of reserves within equity [abstract]
Valuation gain on available-for-sale financial assets	₩ 168,211	₩ 12,534
Other comprehensive loss of investments in associates	(320,060)	(179,167)
Valuation loss on derivatives	(73,828)	(96,418)
Foreign currency translation differences for foreign operations	(9,050)	36,868
Total reserves, net of taxes	₩ (234,727)	₩ (226,183)	₩ 9,303

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Reserves - Changes in Reserves (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reserves within equity [Line Items]
Balance at January 1	₩ (226,183)	₩ 9,303
Changes, net of taxes	(8,544)	(235,486)
Balance at December 31	(234,727)	(226,183)
Valuation gain (loss) on available-for-sale financial assets [Member]
Disclosure of reserves within equity [Line Items]
Balance at January 1	12,534	232,316
Changes, net of taxes	155,677	(219,782)
Balance at December 31	168,211	12,534
Other comprehensive loss of investments in associates [Member]
Disclosure of reserves within equity [Line Items]
Balance at January 1	(179,167)	(169,520)
Changes, net of taxes	(140,893)	(9,647)
Balance at December 31	(320,060)	(179,167)
Valuation gain (loss) on derivatives [Member]
Disclosure of reserves within equity [Line Items]
Balance at January 1	(96,418)	(83,200)
Changes, net of taxes	22,590	(13,218)
Balance at December 31	(73,828)	(96,418)
Foreign currency translation differences for foreign operations [Member]
Disclosure of reserves within equity [Line Items]
Balance at January 1	36,868	29,707
Changes, net of taxes	(45,918)	7,161
Balance at December 31	₩ (9,050)	₩ 36,868

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Reserves - Changes in Valuation Gain on Available-for-sale Financial Assets (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reserves within equity [Line Items]
Balance at January 1	₩ (226,183)	₩ 9,303
Balance at December 31	(234,727)	(226,183)
Valuation gain (loss) on available-for-sale financial assets [Member]
Disclosure of reserves within equity [Line Items]
Balance at January 1	12,534	232,316
Amount recognized as other comprehensive income during the year, net of taxes	132,586	4,606
Amount reclassified through profit or loss, net of taxes	23,091	(224,388)
Balance at December 31	₩ 168,211	₩ 12,534

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Reserves - Changes in Valuation Gain (Loss) on Derivatives (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reserves within equity [Line Items]
Balance at January 1	₩ (226,183)	₩ 9,303
Amount recognized as other comprehensive loss during the year, net of taxes	73,828
Balance at December 31	(234,727)	(226,183)
Valuation gain (loss) on derivatives [Member]
Disclosure of reserves within equity [Line Items]
Balance at January 1	(96,418)	(83,200)
Amount recognized as other comprehensive loss during the year, net of taxes	17,965	(12,213)
Amount reclassified through profit or loss, net of taxes	4,625	(1,005)
Balance at December 31	₩ (73,828)	₩ (96,418)

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Other Operating Income and Expenses - Details of Other Operating Income and Expenses (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Operating Income:
Gain on disposal of property and equipment and intangible assets	₩ 13,991	₩ 6,908	₩ 7,140
Others	18,006	59,640	23,795
Other operating income	31,997	66,548	30,935
Other Operating Expenses:
Communication	27,973	31,196	43,979
Utilities	299,825	277,497	270,621
Taxes and dues	27,819	35,020	36,118
Repair	333,101	326,076	312,517
Research and development	395,276	344,787	315,790
Training	32,853	33,303	37,278
Bad debt for accounts receivable - trade	34,584	37,820	60,450
Travel	24,095	25,263	27,860
Supplies and other	111,170	113,930	176,248
Loss on disposal of property and equipment and intangible assets	60,086	63,797	21,392
Impairment loss on other investment securities	9,003	24,033	42,966
Impairment loss on property and equipment and intangible assets	54,946	24,506	35,845
Donations	112,634	96,633	72,454
Bad debt for accounts receivable - other	5,793	40,312	15,323
Others	101,589	49,593	55,536
Other operating expenses	₩ 1,630,747	₩ 1,523,766	₩ 1,524,377

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Finance Income and Costs - Details of Finance Income and Costs (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finance Income:
Interest income	₩ 76,045	₩ 54,353	₩ 45,884
Gain on sale of accounts receivable - trade	18,548	18,638
Dividends	12,416	19,161	16,102
Gain on foreign currency transactions	13,676	14,186	18,923
Gain on foreign currency translations	7,110	5,085	5,090
Gain on disposal of long-term investment securities	4,890	459,349	10,786
Gain on valuation of derivatives	223,943	4,132	1,927
Reversal of impairment loss on available-for-sale financial assets	9,900
Gain relating to financial assets at fair value through profit or loss	33	25
Gain relating to financial liability at fair value through profit or loss		121	5,188
Finance income	366,561	575,050	103,900
Finance Costs:
Interest expense	299,100	290,454	297,662
Loss on sale of accounts receivable - trade	9,682
Loss on foreign currency transactions	19,263	16,765	17,931
Loss on foreign currency translations	8,419	3,991	4,750
Loss on disposal of long-term investment securities	36,024	2,919	2,599
Loss on settlement of derivatives	10,031	3,428	4,845
Loss relating to financial liability at fair value through profit or loss	678	4,018	526
Impairment loss on long-term investment securities	14,519	5,255	21,787
Other finance costs	35,900
Finance costs	₩ 433,616	₩ 326,830	₩ 350,100

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Finance Income and Costs - Details of Interest Income Included in Finance Income (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Analysis of income and expense [abstract]
Interest income on cash equivalents and short-term financial instruments	₩ 28,130	₩ 20,203	₩ 20,009
Interest income on installment receivables and others	47,915	34,150	25,875
Interest income	₩ 76,045	₩ 54,353	₩ 45,884

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Finance Income and Costs - Details of Interest Expenses Included in Finance Costs (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Analysis of income and expense [abstract]
Interest expense on borrowings	₩ 11,774	₩ 7,962	₩ 19,577
Interest expense on debentures	228,568	239,560	238,450
Interest on finance lease liabilities			58
Others	58,758	42,932	39,577
Interest expense	₩ 299,100	₩ 290,454	₩ 297,662

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Finance Income and Costs - Finance Income and Costs by Category of Financial Instruments (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [Line items]
Finance income	₩ 366,561	₩ 575,050	₩ 103,900
Finance costs	433,616	326,830	350,100
Available-for-sale financial assets	158,440	(223,981)	(3,661)
Finance costs	433,616	326,830	350,100
Derivatives designated as hedging instruments	22,586	(13,218)	(1,271)
Other comprehensive income (loss)	(1,013)	(247,331)	1,835
Financial assets, class [member]
Disclosure of detailed information about financial instruments [Line items]
Finance income	366,251	574,713	97,896
Finance costs	123,485	27,412	45,092
Available-for-sale financial assets	158,440	(223,981)	(3,661)
Finance costs	123,485	27,412	45,092
Derivatives designated as hedging instruments	1,554	(172)	(3,248)
Other comprehensive income (loss)	159,994	(224,153)	(6,909)
Financial liabilities, class [member]
Disclosure of detailed information about financial instruments [Line items]
Finance income	310	337	6,004
Finance costs	310,131	299,418	305,008
Finance costs	310,131	299,418	305,008
Derivatives designated as hedging instruments	21,032	(13,046)	1,977
Other comprehensive income (loss)	21,032	(13,046)	1,977
Financial instruments [member]
Disclosure of detailed information about financial instruments [Line items]
Other comprehensive income (loss)	181,026	(237,199)	(4,932)
Financial assets at fair value through profit or loss [member]
Disclosure of detailed information about financial instruments [Line items]
Finance income	223,976	4,157	1,927
Finance costs		2,791	4,188
Finance costs		2,791	4,188
Available- for-sale financial assets [Member]
Disclosure of detailed information about financial instruments [Line items]
Finance income	30,598	484,300	31,220
Finance costs	86,445	8,174	24,386
Finance costs	86,445	8,174	24,386
Loans and receivables [member]
Disclosure of detailed information about financial instruments [Line items]
Finance income	111,677	86,256	64,749
Finance costs	37,040	15,810	15,861
Finance costs	37,040	15,810	15,861
Financial liabilities at fair value through profit or loss [member]
Disclosure of detailed information about financial instruments [Line items]
Finance income		121	5,188
Finance costs	678	4,018	526
Finance costs	678	4,018	526
Financial liabilities at amortised cost [Member]
Disclosure of detailed information about financial instruments [Line items]
Finance income	310	216	816
Finance costs	299,422	295,400	304,482
Finance costs	299,422	295,400	304,482
Derivatives hedging instrument [member]
Disclosure of detailed information about financial instruments [Line items]
Finance costs	10,031	637	657
Finance costs	₩ 10,031	₩ 637	₩ 657

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Finance Income and Costs - Details of Impairment Losses for Financial Assets (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [Line items]
Impairment losses for financial assets	₩ 54,896	₩ 83,387	₩ 97,560
Available- for-sale financial assets [Member]
Disclosure of detailed information about financial instruments [Line items]
Impairment losses for financial assets	14,519	5,255	21,787
Accounts receivable - trade [member]
Disclosure of detailed information about financial instruments [Line items]
Impairment losses for financial assets	34,584	37,820	60,450
Other receivables [member]
Disclosure of detailed information about financial instruments [Line items]
Impairment losses for financial assets	₩ 5,793	₩ 40,312	₩ 15,323

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Income Tax Expense - Summary of Income Tax Expenses (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax expense
Current year	₩ 424,773	₩ 473,543	₩ 417,022
Current tax of prior years	(105,158)	(11,925)	(4,124)
Current tax expense	319,615	461,618	412,898
Deferred tax expense
Changes in net deferred tax assets	426,039	(25,580)	106,399
Others (tax rate differences, etc.)			183
Income tax expense	₩ 745,654	₩ 436,038	₩ 519,480

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Income Tax Expense - Difference Between Income Taxes Computed using the Statutory Corporate Income Tax Rates and the Recorded Income Taxes (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of average effective tax rate and applicable tax rate [abstract]
Income taxes at statutory income tax rate	₩ 823,124	₩ 506,804	₩ 492,096
Non-taxable income	(40,080)	(38,989)	(85,589)
Non-deductible expenses	31,285	52,648	44,770
Tax credit and tax reduction	(34,300)	(29,484)	(25,756)
Changes in unrecognized deferred taxes	31,857	(84,276)	83,623
Others (income tax refund, etc.)	(66,232)	29,335	10,336
Income tax expense	₩ 745,654	₩ 436,038	₩ 519,480

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Income Tax Expense - Difference Between Income Taxes Computed using the Statutory Corporate Income Tax Rates and the Recorded Income Taxes (Parenthetical) (Detail)		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017
Disclosure of Income Taxes [Line Items]
Income tax rate		24.20%
Income tax rate for taxable income in excess of W300,000 million [Member]
Disclosure of Income Taxes [Line Items]
Income tax rate	27.50%

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Income Tax Expense - Deferred Taxes Directly Charged to (Credited from) Equity (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred taxes directly charged to (credited from) equity	₩ (57,544)	₩ 90,623	₩ 4,669
Valuation gain (loss) on available-for-sale financial assets [Member]
Deferred taxes directly charged to (credited from) equity	(55,883)	82,993	2,461
Share of other comprehensive income (loss) of associates [Member]
Deferred taxes directly charged to (credited from) equity	(260)	2	(63)
Valuation gain (loss) on derivatives [Member]
Deferred taxes directly charged to (credited from) equity	(3,019)	4,454	(448)
Reserve of remeasurements of defined benefit plans [Member]
Deferred taxes directly charged to (credited from) equity	₩ 1,618	₩ 3,174	₩ 2,719

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Income Tax Expense - Details of the Changes in Deferred Tax Assets (Liabilities) (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	₩ (404,654)	₩ (520,857)
Deferred tax expense (income)	(426,039)	25,580
Directly charged to (credited from) equity	(57,544)	90,623	₩ 4,669
Others	(2,324)
Ending	(890,561)	(404,654)	(520,857)
Allowance for doubtful accounts [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	61,911	59,957
Deferred tax expense (income)	5,091	1,954
Ending	67,002	61,911	59,957
Accrued interest income [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	(616)	(2,567)
Deferred tax expense (income)	(1,851)	1,951
Ending	(2,467)	(616)	(2,567)
Available- for-sale financial assets [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	101,472	30,365
Deferred tax expense (income)	8,192	(11,886)
Directly charged to (credited from) equity	(55,883)	82,993
Ending	53,781	101,472	30,365
Investments in subsidiaries, associates and joint ventures [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	(476,098)	(355,273)
Deferred tax expense (income)	(461,271)	(120,827)
Directly charged to (credited from) equity	(260)	2
Ending	(937,629)	(476,098)	(355,273)
Property and equipment (depreciation) [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	(253,323)	(327,572)
Deferred tax expense (income)	17,980	74,249
Ending	(235,343)	(253,323)	(327,572)
Provisions [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	7,448	2,485
Deferred tax expense (income)	(5,136)	4,963
Ending	2,312	7,448	2,485
Retirement benefit obligation [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	35,505	28,327
Deferred tax expense (income)	1,237	4,004
Directly charged to (credited from) equity	1,618	3,174
Ending	38,360	35,505	28,327
Valuation gain (loss) on derivatives [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	28,975	24,521
Directly charged to (credited from) equity	(3,019)	4,454
Ending	25,956	28,975	24,521
Foreign currency translation differences for foreign operations [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	19,369	19,517
Deferred tax expense (income)	2,562	(148)
Ending	21,931	19,369	19,517
Reserve for research and manpower development [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	(4,775)	(7,162)
Deferred tax expense (income)	2,388	2,387
Ending	(2,387)	(4,775)	(7,162)
Goodwill [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	3,105	3,713
Deferred tax expense (income)	(938)	(608)
Ending	2,167	3,105	3,713
Others [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	34,911	(23,782)
Deferred tax expense (income)	(29,248)	58,693
Others	(2,324)
Ending	3,339	34,911	(23,782)
Temporary differences [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	(442,116)	(545,406)
Deferred tax expense (income)	(460,994)	12,667
Directly charged to (credited from) equity	(57,544)	90,623
Others	(2,324)
Ending	(962,978)	(442,116)	(545,406)
Tax loss carryforwards [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning	37,462	24,549
Deferred tax expense (income)	34,955	12,913
Ending	₩ 72,417	37,462	24,549
Unearned revenue (activation fees) [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning		2,065
Deferred tax expense (income)		₩ (2,065)
Ending			₩ 2,065

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Income Tax Expense - Details of Temporary Differences, Unused Tax Loss Carryforwards and Unused Tax Credits Carryforwards Which are Not Recognized as Deferred Tax Assets (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Unused tax loss carryforwards	₩ 921,309	₩ 755,050
Unused tax credit carryforwards	4,092	1,211
Allowance for doubtful accounts [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Temporary differences	88,521	165,935
Investments in subsidiaries, associates and joint ventures [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Temporary differences	168,268	228,025
Others [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Temporary differences	₩ 425,653	₩ 320,260

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Income Tax Expense - Unused Tax Loss Carryforwards and Unused Tax Credit Carryforwards Which are Not Recognized as Deferred Tax Assets (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Unused tax loss carryforwards	₩ 921,309	₩ 755,050
Unused tax credit carryforwards	4,092	₩ 1,211
Less than 1 year [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Unused tax credit carryforwards	869
1 ~ 2 years [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Unused tax loss carryforwards	7,686
Unused tax credit carryforwards	101
2 ~ 3 years [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Unused tax loss carryforwards	358,237
Unused tax credit carryforwards	119
More than 3 years [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Unused tax loss carryforwards	555,386
Unused tax credit carryforwards	₩ 3,003

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Earnings per Share - Summary of Basic Earnings Per Share (Detail) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic earnings per share attributable to owners of the Parent Company:
Profit attributable to owners of the Parent Company	₩ 2,599,829	₩ 1,675,967	₩ 1,518,604
Interest on hybrid bonds	(16,840)	(16,840)	(16,840)
Profit attributable to owners of the Parent Company on common shares	₩ 2,582,989	₩ 1,659,127	₩ 1,501,764
Weighted average number of common shares outstanding	70,609,160	70,609,160	71,551,966
Basic earnings per share (in won)	₩ 36,582	₩ 23,497	₩ 20,988

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Earnings per Share - Weighted Average Number of Common Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings per share [abstract]
Issued common shares at January 1	80,745,711	80,745,711	80,745,711
Effect of treasury shares	(10,136,551)	(10,136,551)	(9,193,745)
Weighted average number of common shares outstanding at December 31	70,609,160	70,609,160	71,551,966

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Earnings per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings per share [abstract]
Potentially dilutive shares	0	0	0

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Dividends - Details of Dividend Declared (Detail) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of dividends [Line Items]
Dividend type	Cash dividends	Cash dividends	Cash dividends
Number of shares outstanding	70,609,160	70,609,160
Face value (in won)	₩ 500
Dividends	₩ 706,091	₩ 706,091	₩ 708,111
Interim [Member]
Disclosure of dividends [Line Items]
Dividend type	Cash dividends (Interim)	Cash dividends (Interim)	Cash dividends (Interim)
Number of shares outstanding	70,609,160	70,609,160	72,629,160
Face value (in won)	₩ 500	₩ 500	₩ 500
Dividend ratio	200.00%	200.00%	200.00%
Dividends	₩ 70,609	₩ 70,609	₩ 72,629
Year-end [Member]
Disclosure of dividends [Line Items]
Dividend type	Cash dividends (Year-end)	Cash dividends (Year-end)	Cash dividends (Year-end)
Number of shares outstanding	70,609,160	70,609,160	70,609,160
Face value (in won)	₩ 500	₩ 500	₩ 500
Dividend ratio	1800.00%	1800.00%	1800.00%
Dividends	₩ 635,482	₩ 635,482	₩ 635,482

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Dividends - Dividends Yield Ratios (Detail) - ₩ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Dividends [abstract]
Dividend type	Cash dividends	Cash dividends	Cash dividends
Dividend per share	₩ 10,000	₩ 10,000	₩ 10,000
Closing price at year-end	₩ 267,000	₩ 224,000	₩ 215,500
Dividend yield ratio	3.75%	4.46%	4.64%

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Categories of Financial Instruments - Financial Assets by Category (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of financial assets [line items]
Cash and cash equivalents	₩ 1,457,735	₩ 1,505,242	₩ 768,922	₩ 834,429
Short-term loans	62,830	58,979
Financial instruments	618,002	469,705
Accounts receivable - other	1,260,835	1,121,444
Short-term investment securities	144,386	107,364
Accrued income	3,979	2,780
Long-term investment securities	887,007	828,521
Other current assets	3,927	3,937
Accounts receivable - trade	2,138,755	2,261,311
Long-term loans	50,874	65,476
Long-term accounts receivable - other	287,048	149,669
Guarantee deposits	292,590	298,964
Loans and other receivables	1,962,083	1,701,249
Derivative financial assets	253,213	214,770
Financial assets	7,461,181	7,088,162
Financial assets at fair value through profit or loss [member]
Disclosure of financial assets [line items]
Short-term investment securities	97,003
Derivative financial assets	231,311	7,368
Financial assets	328,314	7,368
Available- for-sale financial assets [Member]
Disclosure of financial assets [line items]
Short-term investment securities	47,383	107,364
Long-term investment securities	887,007	828,521
Financial assets	934,390	935,885
Loans and receivables [member]
Disclosure of financial assets [line items]
Cash and cash equivalents	1,457,735	1,505,242
Financial instruments	618,002	469,705
Accounts receivable - trade	2,138,755	2,261,311
Loans and other receivables	1,962,083	1,701,249
Financial assets	6,176,575	5,937,507
Derivatives hedging instrument [member]
Disclosure of financial assets [line items]
Derivative financial assets	21,902	207,402
Financial assets	₩ 21,902	₩ 207,402

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Categories of Financial Instruments - Financial Liabilities by Category (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial liabilities [line items]
Accounts payable - other	₩ 1,867,074	₩ 1,767,799
Accounts payable - trade	351,711	402,445
Withholdings	1,736	1,525
Derivative financial liabilities	39,470	87,153
Accrued expenses	1,327,906	1,125,816
Borrowings	382,817	175,521
Current portion of long-term payables - other	302,703	301,773
Debentures	7,086,187	7,194,206
Long-term payables - other	1,346,763	1,624,590
Other non-currentliabilities	19,337	21,231
Accounts payable - other and others	4,865,519	4,842,734
Financial liabilities	12,725,704	12,702,059
Financial liabilities at fair value through profit or loss [member]
Disclosure of financial liabilities [line items]
Debentures	60,278	59,600
Financial liabilities	60,278	59,600
Financial liabilities measured at amortized cost [Member]
Disclosure of financial liabilities [line items]
Accounts payable - trade	351,711	402,445
Borrowings	382,817	175,521
Debentures	7,025,909	7,134,606
Accounts payable - other and others	4,865,519	4,842,734
Financial liabilities	12,625,956	12,555,306
Derivatives hedging instrument [member]
Disclosure of financial liabilities [line items]
Derivative financial liabilities	39,470	87,153
Financial liabilities	₩ 39,470	₩ 87,153

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Financial Risk Management - Monetary Assets and Liabilities Denominated in Foreign Currencies (Detail) € in Thousands, ¥ in Thousands, $ in Thousands, ₩ in Millions	Dec. 31, 2017 KRW (₩)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 JPY (¥)	Dec. 31, 2016 KRW (₩)
Disclosure of detailed information about financial instruments [Line items]
Monetary assets denominated in foreign currencies	₩ 7,461,181				₩ 7,088,162
Monetary liabilities denominated in foreign currencies	12,725,704				₩ 12,702,059
Currency risk [member]
Disclosure of detailed information about financial instruments [Line items]
Monetary assets denominated in foreign currencies	160,068	$ 124,901	€ 15,669	¥ 596,059
Monetary liabilities denominated in foreign currencies	1,949,485	$ 1,817,808	€ 63	¥ 169,729
Currency risk [member] | US Dollar [member]
Disclosure of detailed information about financial instruments [Line items]
Monetary assets denominated in foreign currencies	133,836
Monetary liabilities denominated in foreign currencies	1,947,599
Currency risk [member] | Euro [member]
Disclosure of detailed information about financial instruments [Line items]
Monetary assets denominated in foreign currencies	20,044
Monetary liabilities denominated in foreign currencies	80
Currency risk [member] | Yen [member]
Disclosure of detailed information about financial instruments [Line items]
Monetary assets denominated in foreign currencies	5,658
Monetary liabilities denominated in foreign currencies	1,611
Currency risk [member] | Other currencies [member]
Disclosure of detailed information about financial instruments [Line items]
Monetary assets denominated in foreign currencies	530
Monetary liabilities denominated in foreign currencies	₩ 195

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Financial Risk Management - Impact on Income Before Income Tax of a Hypothetical Change in Exchange Rates (Detail) - Currency risk [member] ₩ in Millions	Dec. 31, 2017 KRW (₩)
If increased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	₩ 8,026
If decreased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	(8,026)
US Dollar [member] | If increased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	5,590
US Dollar [member] | If decreased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	(5,590)
Euro [member] | If increased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	1,997
Euro [member] | If decreased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	(1,997)
Yen [member] | If increased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	405
Yen [member] | If decreased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	(405)
Other currencies [member] | If increased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	34
Other currencies [member] | If decreased by 10% [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (reduce) the Group's income before income tax	₩ (34)

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Financial Risk Management - Additional Information (Detail) - KRW (₩)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about financial instruments [Line items]
Long-term borrowings	₩ 252,817,000,000	₩ 172,907,000,000
Bonds	7,086,187,000,000	7,194,206,000,000
Transfers from level 2 to level 1	0
At cost [member]
Disclosure of detailed information about financial instruments [Line items]
Available-for-sale financial assets	₩ 199,903,000,000	₩ 194,600,000,000
Interest rate risk [member]
Disclosure of detailed information about financial instruments [Line items]
Hypothetical increase (decrease) in interest rate	1.00%
Hypothetical increase (decrease) in interest rate, effect on income before income taxes	₩ 707,000,000
Floating-rate [member]
Disclosure of detailed information about financial instruments [Line items]
Long-term borrowings	228,300,000,000
Bonds	321,420,000,000
Equity investments [member]
Disclosure of detailed information about financial instruments [Line items]
Available-for-sale financial assets	₩ 734,487,000,000

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Financial Risk Management - Maximum Credit Exposure (Detail) - KRW (₩)	Dec. 31, 2017	Dec. 31, 2016
Disclosure of credit risk exposure [line items]
Maximum credit exposure	₩ 6,227,140,000,000	₩ 6,158,872,000,000
Cash and cash equivalents [Member]
Disclosure of credit risk exposure [line items]
Maximum credit exposure	1,457,416,000,000	1,505,082,000,000
Financial instruments [member]
Disclosure of credit risk exposure [line items]
Maximum credit exposure	618,002,000,000	469,705,000,000
Available- for-sale financial assets [Member]
Disclosure of credit risk exposure [line items]
Maximum credit exposure	19,928,000,000	6,755,000,000
Accounts receivable - trade [member]
Disclosure of credit risk exposure [line items]
Maximum credit exposure	2,138,755,000,000	2,261,311,000,000
Loans and receivables [member]
Disclosure of credit risk exposure [line items]
Maximum credit exposure	1,962,083,000,000	1,701,249,000,000
Derivatives hedging instrument [member]
Disclosure of credit risk exposure [line items]
Maximum credit exposure	₩ 30,956,000,000	₩ 214,770,000,000

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Financial Risk Management - Contractual Maturities of Financial Liabilities (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Accounts payable - trade, carrying amount	₩ 351,711	₩ 402,445
Borrowings, carrying amount	382,817	175,521
Debentures, carrying amount	7,086,187	7,194,206
Accounts payable - other and others, carrying amount	4,865,519	₩ 4,842,734
Non-derivative financial liabilities, carrying amount	12,686,234
Accounts payable - trade, contractual cash flows	351,711
Borrowings, contractual cash flows	397,776
Debentures, contractual cash flows	8,230,952
Accounts payable - other and others, contractual cash flows	5,030,105
Non-derivative financial liabilities, contractual cash flows	14,010,544
Less than 1 year [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Accounts payable - trade, contractual cash flows	351,711
Borrowings, contractual cash flows	177,910
Debentures, contractual cash flows	1,682,206
Accounts payable - other and others, contractual cash flows	3,519,489
Non-derivative financial liabilities, contractual cash flows	5,731,316
1-5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings, contractual cash flows	219,866
Debentures, contractual cash flows	3,675,178
Accounts payable - other and others, contractual cash flows	1,093,611
Non-derivative financial liabilities, contractual cash flows	4,988,655
More than 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debentures, contractual cash flows	2,873,568
Accounts payable - other and others, contractual cash flows	417,005
Non-derivative financial liabilities, contractual cash flows	₩ 3,290,573

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Financial Risk Management - Contractual Maturities of Financial Liabilities (Parenthetical) (Detail) - Dec. 31, 2017 ₩ in Millions	KRW (₩)	USD ($)
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Accounts payable - other and others, contractual cash flows | ₩	₩ 5,030,105
Celcom planet [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Accounts payable - other and others, contractual cash flows | $		$ 12,240,000

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Financial Risk Management - Periods in Which Cash Flows from Cash Flow Hedge Derivatives are Expected to Occur (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of maturity analysis for derivative financial liabilities [line items]
Assets, carrying amount	₩ 21,902
Liabilities, carrying amount	(39,470)	₩ (87,153)
Net assets, carrying amount	(17,568)
Assets, contractual cash flows	17,118
Liabilities, contractual cash flows	(40,220)
Net assets, contractual cash flows	(23,102)
Less than 1 year [Member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Assets, contractual cash flows	7,446
Liabilities, contractual cash flows	(28,960)
Net assets, contractual cash flows	(21,514)
1-5 years [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Assets, contractual cash flows	28,075
Liabilities, contractual cash flows	(11,260)
Net assets, contractual cash flows	16,815
More than 5 years [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Assets, contractual cash flows	(18,403)
Net assets, contractual cash flows	₩ (18,403)

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Financial Risk Management - Debt-equity Ratio (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of detailed information about financial instruments [abstract]
Total liabilities	₩ 15,399,474	₩ 15,181,233
Total equity	₩ 18,029,195	₩ 16,116,430	₩ 15,374,096	₩ 15,248,270
Debt-equity ratios	85.41%	94.20%

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Financial Risk - Fair Value and Carrying Amount of Financial Assets and Liabilities Including Fair Value Hierarchy (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about financial instruments [Line items]
Borrowings	₩ 382,817	₩ 175,521
Derivative financial assets	21,902
Debentures	7,086,187	7,194,206
Financial assets	7,461,181	7,088,162
Derivative financial liabilities	39,470	87,153
Financial liabilities	12,725,704	12,702,059
Measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Financial assets at fair value through profit or loss	328,314	7,368
Derivative financial assets	21,902	207,402
Available-for-sale financial assets	734,487	741,285
Financial assets	1,084,703	956,055
Financial liabilities at fair value through profit or loss	60,278	59,600
Derivative financial liabilities	39,470	87,153
Financial liabilities	99,748	146,753
Not measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Borrowings	383,748	177,600
Debentures	7,325,370	7,568,361
Long-term payables - other	1,766,451	2,103,788
Financial liabilities	9,475,569	9,849,749
Carrying amount [member] | Measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Financial assets at fair value through profit or loss	328,314	7,368
Derivative financial assets	21,902	207,402
Available-for-sale financial assets	734,487	741,285
Financial assets	1,084,703	956,055
Financial liabilities at fair value through profit or loss	60,278	59,600
Derivative financial liabilities	39,470	87,153
Financial liabilities	99,748	146,753
Carrying amount [member] | Not measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Borrowings	382,817	175,521
Debentures	7,025,909	7,134,606
Long-term payables - other	1,649,466	1,926,363
Financial liabilities	9,058,192	9,236,490
Level 1 [member] | Measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Available-for-sale financial assets	589,202	526,363
Financial assets	589,202	526,363
Level 2 [member] | Measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Financial assets at fair value through profit or loss	106,057	7,368
Derivative financial assets	21,902	207,402
Available-for-sale financial assets	47,383	107,364
Financial assets	175,342	322,134
Financial liabilities at fair value through profit or loss	60,278	59,600
Derivative financial liabilities	39,470	87,153
Financial liabilities	99,748	146,753
Level 2 [member] | Not measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Borrowings	383,748	177,600
Debentures	7,325,370	7,568,361
Long-term payables - other	1,766,451	2,103,788
Financial liabilities	9,475,569	9,849,749
Level 3 [member]
Disclosure of detailed information about financial instruments [Line items]
Available-for-sale financial assets	15,342
Level 3 [member] | Measured at fair value [member]
Disclosure of detailed information about financial instruments [Line items]
Financial assets at fair value through profit or loss	222,257
Available-for-sale financial assets	97,902	107,558
Financial assets	₩ 320,159	₩ 107,558

XML

Financial Risk Management - Interest Rates Used by the Group for the Fair Value Measurement (Detail)	12 Months Ended
	Dec. 31, 2017
Bottom of range [member] | Derivatives hedging instrument [member]
Disclosure of detailed information about financial instruments [Line items]
Interest rate	1.54%
Bottom of range [member] | Borrowings and debentures [member]
Disclosure of detailed information about financial instruments [Line items]
Interest rate	2.48%
Bottom of range [member] | Long-term payables - other [member]
Disclosure of detailed information about financial instruments [Line items]
Interest rate	2.23%
Top of range [member] | Derivatives hedging instrument [member]
Disclosure of detailed information about financial instruments [Line items]
Interest rate	2.67%
Top of range [member] | Borrowings and debentures [member]
Disclosure of detailed information about financial instruments [Line items]
Interest rate	2.55%
Top of range [member] | Long-term payables - other [member]
Disclosure of detailed information about financial instruments [Line items]
Interest rate	2.60%

XML

Financial Risk Management - Changes of Financial Assets Classified as Level 3 (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)
Disclosure of fair value measurement of assets [line items]
Balance at beginning	₩ 31,297,663
Balance at ending	33,428,669
Level 3 [member]
Disclosure of fair value measurement of assets [line items]
Valuation	222,257
Financial assets at fair value through profit or loss [member] | Level 3 [member]
Disclosure of fair value measurement of assets [line items]
Valuation	222,257
Balance at ending	222,257
Available- for-sale financial assets [Member] | Level 3 [member]
Disclosure of fair value measurement of assets [line items]
Balance at beginning	107,558
Transfer	3,938
Other comprehensive loss	(8,942)
Disposal	(4,652)
Balance at ending	₩ 97,902

XML

Financial Risk Management - Changes of Financial Assets Classified as Level 3 (Parenthetical) (Detail) - Level 3 [member] ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)
Disclosure of fair value measurement of assets [line items]
Financial assets at FVTPL and gain on valuation of derivatives	₩ 222,257
Available-for-sale financial assets	₩ 15,342

XML

Financial Risk Management - Carrying Amount of Financial Instruments Recognized of Which Offset Agreements are Applicable (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about financial instruments [Line items]
Financial assets, Gross financial instruments recognized	₩ 119,791	₩ 201,701
Financial assets, Amount offset	(92,409)	(103,852)
Financial assets, Net financial instruments presented on the statements of financial position	27,382	97,849
Financial assets, Relevant amount not offset on the statements of financial position, Financial instruments	(19,875)	(87,153)
Financial assets, Net amount	7,507	10,696
Financial liabilities, Gross financial instruments recognized	112,284	(191,005)
Financial liabilities, Amount offset	92,409	(103,852)
Financial liabilities, Net financial instruments presented on the statements of financial position	19,875	(87,153)
Financial liabilities, Relevant amount not offset on the statements of financial position, Financial instruments	19,875	(87,153)
Financial liabilities, Net amount	0	0
Derivatives hedging instrument [member]
Disclosure of detailed information about financial instruments [Line items]
Financial assets, Gross financial instruments recognized	26,645	87,566
Financial assets, Net financial instruments presented on the statements of financial position	26,645	87,566
Financial assets, Relevant amount not offset on the statements of financial position, Financial instruments	(19,875)	(87,153)
Financial assets, Net amount	6,770	413
Financial liabilities, Gross financial instruments recognized	19,875	(87,153)
Financial liabilities, Net financial instruments presented on the statements of financial position	19,875	(87,153)
Financial liabilities, Relevant amount not offset on the statements of financial position, Financial instruments	19,875	(87,153)
Financial liabilities, Net amount	0	0
Accounts payable - other and others [member]
Disclosure of detailed information about financial instruments [Line items]
Financial liabilities, Gross financial instruments recognized	92,409	(103,852)
Financial liabilities, Amount offset	92,409	(103,852)
Financial liabilities, Net amount	0	0
Accounts receivable - trade and others [member]
Disclosure of detailed information about financial instruments [Line items]
Financial assets, Gross financial instruments recognized	93,146	114,135
Financial assets, Amount offset	(92,409)	(103,852)
Financial assets, Net financial instruments presented on the statements of financial position	737	10,283
Financial assets, Net amount	₩ 737	₩ 10,283

XML

Related Parties and Others - Compensation for the Key Management (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of transactions between related parties [abstract]
Salaries	₩ 2,169	₩ 1,645	₩ 1,971
Defined benefits plan expenses	258	424	626
Share option	414
Compensation for the key management	₩ 2,841	₩ 2,069	₩ 2,597

XML

Related Parties and Others - Transactions with Related Parties (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	₩ 259,249	₩ 221,407	₩ 193,284
Operating expense and others	2,266,988	2,185,277	2,136,720
Acquisition of property and equipment	1,070,246	876,996	835,880
Collection of loans	204	3,194	204
Loans		1,100	8,977
SK hynix Inc. [member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	123,873	100,861	55,949
Operating expense and others	251	306	2,384
Other associates [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	10,720	8,018	6,397
Operating expense and others	33,389	21,853	11,917
Acquisition of property and equipment	940	1,573	1,864
Collection of loans	204	3,194
Loans		1,100	690
SK Holdings Co., Ltd. (formerly, SK Holdings Co., Ltd.) [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others			1,299
Operating expense and others			212,378
Acquisition of property and equipment			117
SK Holdings Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	25,049	23,104
Operating expense and others	600,600	652,855
Acquisition of property and equipment	283,556	235,502
F&U Credit information Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	3,431	2,865	2,510
Operating expense and others	52,150	47,905	43,967
Acquisition of property and equipment	153
HappyNarae Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	3,025	304	297
Operating expense and others	29,276	15,506	6,886
Acquisition of property and equipment	68,472	38,984	13,495
KEB HanaCard Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	17,873	19,730	21,414
Operating expense and others	15,045	14,804	16,057
Associates [member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	158,922	131,778	90,416
Operating expense and others	130,111	100,374	99,755
Acquisition of property and equipment	69,565	40,557	15,359
Collection of loans	204	3,194	204
Loans		1,100	8,977
SK Engineering & Construction Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	5,865	5,916	15,598
Operating expense and others	1,077	1,739	27,243
Acquisition of property and equipment		10,694	240,701
SK Networks Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	21,694	13,756	11,923
Operating expense and others	1,220,251	1,131,567	1,257,975
Acquisition of property and equipment	671		2
SK Networks Services Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	510	1,248	10,491
Operating expense and others	96,949	94,906	94,097
Acquisition of property and equipment	6,346	6,793	6,472
SK Telesys Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	417	419	397
Operating expense and others	51,394	52,488	48,900
Acquisition of property and equipment	152,659	142,605	141,870
SK TNS Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	137	109
Operating expense and others	37,051	48,192
Acquisition of property and equipment	494,621	387,496
SK Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	8,505	7,670	9,930
Operating expense and others	779	834	978
SK Gas Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	2,727	2,500	3,561
Operating expense and others	4	4	2
SK Innovation Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	7,639	9,757
Operating expense and others	950	915
Acquisition of property and equipment		1,080
SK Shipping Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	3,183	5,435
Operating expense and others	35
Ko-one energy service Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	5,164	6,005
Operating expense and others	44	46
SK Infosec Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	1,185	230
Operating expense and others	52,634	53,068
Acquisition of property and equipment	15,648	19,882
SKC INFRA SERVICE Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	19	43
Operating expense and others	46,900	30,663
Acquisition of property and equipment	47,163	32,141
Miscellaneous other related parties [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	18,233	13,437	29,409
Operating expense and others	28,209	17,626	71,314
Acquisition of property and equipment	17	246	194,945
Others [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others	75,278	66,525	81,309
Operating expense and others	1,536,277	1,432,048	1,500,509
Acquisition of property and equipment	₩ 717,125	₩ 600,937	583,990
SK Holdings Co., Ltd. (formerly, SK C&C Co., Ltd.) [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others			20,260
Operating expense and others			324,078
Acquisition of property and equipment			236,414
Parent [member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others			21,559
Operating expense and others			536,456
Acquisition of property and equipment			236,531
SK Wyverns Baseball Club., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Operating Operating revenue and others			3,849
Operating expense and others			18,544
Collection of loans			204
Xian Tianlong Science and Technology Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Loans			₩ 8,287

XML

Related Parties and Others - Transactions with Related Parties (Parenthetical) (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of transactions between related parties [Line Items]
Dividends received	₩ 12,416	₩ 19,161	₩ 16,102
SK hynix Inc. [member]
Disclosure of transactions between related parties [Line Items]
Dividends received	87,660	73,050	43,830
Other associates [Member] | Korea IT fund [member]
Disclosure of transactions between related parties [Line Items]
Dividends received		6,082	2,103
Other associates [Member] | Uni SK [Member]
Disclosure of transactions between related parties [Line Items]
Dividends received			457
Other associates [Member] | Korea IT Fund and Others [Member]
Disclosure of transactions between related parties [Line Items]
Dividends received	6,597
SK Holdings Co., Ltd. (formerly, SK Holdings Co., Ltd.) [Member]
Disclosure of transactions between related parties [Line Items]
Dividends paid by the Parent Company			₩ 191,416
SK Holdings Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Dividends paid by the Parent Company	₩ 203,635	₩ 203,635

XML

Related Parties and Others - Account Balances with Related Parties (Detail) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Loans [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	₩ 29,790	₩ 31,247
Loans [member] | Daehan Kanggun BcN Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	22,147	22,147
Loans [member] | Xian Tianlong Science and Technology Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	7,032	8,287
Loans [member] | Other associates [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	611	813
Loans [member] | Associates [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	29,790	31,247
Accounts receivable - trade and others [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	64,619	82,385
Accounts receivable - trade and others [member] | SK Holdings Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	2,068	3,519
Accounts receivable - trade and others [member] | HappyNarae Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	15	18
Accounts receivable - trade and others [member] | F&U Credit information Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	21	34
Accounts receivable - trade and others [member] | SK hynix Inc. [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	2,803	22,379
Accounts receivable - trade and others [member] | Wave City Development Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	38,412	38,412
Accounts receivable - trade and others [member] | KEB HanaCard Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	1,427	1,619
Accounts receivable - trade and others [member] | S.M. Culture & Contents Co., Ltd [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	448
Accounts receivable - trade and others [member] | Other associates [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	2,272	4,191
Accounts receivable - trade and others [member] | Associates [member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	45,398	66,653
Accounts receivable - trade and others [member] | SK Engineering & Construction Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	2,033	1,808
Accounts receivable - trade and others [member] | SK Networks Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	3,050	3,254
Accounts receivable - trade and others [member] | SK Networks Services Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	15	13
Accounts receivable - trade and others [member] | SK Telesys Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	36	20
Accounts receivable - trade and others [member] | SK TNS Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	3	3
Accounts receivable - trade and others [member] | SK Innovation Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	4,112	1,350
Accounts receivable - trade and others [member] | SK Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	2,965	1,213
Accounts receivable - trade and others [member] | SK Gas Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	1,941	1,769
Accounts receivable - trade and others [member] | Miscellaneous other related parties [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	2,998	2,783
Accounts receivable - trade and others [member] | Others [Member]
Disclosure of transactions between related parties [Line Items]
Accounts receivable	17,153	12,213
Accounts payable - other and others [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	681,916	571,711
Accounts payable - other and others [member] | SK Holdings Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	148,066	149,574
Accounts payable - other and others [member] | HappyNarae Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	6,865	21,063
Accounts payable - other and others [member] | F&U Credit information Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	1,612	1,328
Accounts payable - other and others [member] | SK hynix Inc. [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	94	92
Accounts payable - other and others [member] | KEB HanaCard Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	11,099	7,676
Accounts payable - other and others [member] | S.M. Culture & Contents Co., Ltd [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	8,963
Accounts payable - other and others [member] | Other associates [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	1,164	945
Accounts payable - other and others [member] | Associates [member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	29,797	31,104
Accounts payable - other and others [member] | SK Engineering & Construction Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	69	4,975
Accounts payable - other and others [member] | SK Networks Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	267,297	247,728
Accounts payable - other and others [member] | SK Networks Services Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	9,522	13,913
Accounts payable - other and others [member] | SK Telesys Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	58,346	24,918
Accounts payable - other and others [member] | SK TNS Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	140,311	68,276
Accounts payable - other and others [member] | SK Innovation Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	599	892
Accounts payable - other and others [member] | SK Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	582	113
Accounts payable - other and others [member] | SK Gas Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	9	9
Accounts payable - other and others [member] | Miscellaneous other related parties [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	27,318	30,209
Accounts payable - other and others [member] | Others [Member]
Disclosure of transactions between related parties [Line Items]
Accounts payable	₩ 504,053	₩ 391,033

XML

Related Parties and Others - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 USD ($)
Celcom planet [member]
Disclosure of transactions between related parties [Line Items]
Payment guarantees for borrowings	$ 12,240,000

XML

Commitments and Contingencies - Additional Information (Detail) - KRW (₩)	Dec. 31, 2017	Dec. 31, 2016
Commitments and contingencies [Line Items]
Short-term financial instruments as collateral for guarantees	₩ 616,780,000,000	₩ 468,768,000,000
Accounts receivables - other	1,962,083,000,000	₩ 1,701,249,000,000
Sales of handsets [member]
Commitments and contingencies [Line Items]
Accounts receivables - other	1,111,614,000,000
Legal proceedings provision [member]
Commitments and contingencies [Line Items]
Provisions for legal claims and litigation	0
SK Broadband Co., Ltd. [member]
Commitments and contingencies [Line Items]
Properties pledged as collateral for leases on buildings	4,144,000,000
Short-term financial instruments as collateral for guarantees	₩ 300,000,000

XML

Statements of Cash Flows - Adjustments for Income and Expenses from Operating Activities (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Adjustments to reconcile profit (loss) [abstract]
Interest income	₩ (76,045)	₩ (54,353)	₩ (45,884)
Dividend	(12,416)	(19,161)	(16,102)
Gain on foreign currency translation	(7,110)	(5,085)	(5,090)
Gain on disposal of long-term investment securities	(4,890)	(459,349)	(10,786)
Gain on valuation of derivatives	(223,943)	(4,132)	(1,927)
Gain relating to investments in associates and joint ventures, net	(2,245,732)	(544,501)	(786,140)
Gain on sale of accounts receivable - trade	(18,548)	(18,638)
Gain on disposal of property and equipment and intangible assets	(13,991)	(6,908)	(7,140)
Gain relating to financial assets at fair value through profit or loss	(33)	(25)
Gain related to financial liabilities at fair value through profit or loss		(121)	(5,188)
Reversal of impairment loss on available-for-sale financial assets	(9,900)
Other income	(1,129)	(2,123)	(7,577)
Interest expenses	299,100	290,454	297,662
Loss on foreign currency translation	8,419	3,991	4,750
Loss on disposal of long-term investment securities	36,024	2,919	2,599
Other finance costs	14,519	5,255	21,787
Loss on sale of accounts receivable - trade	9,682
Loss on settlement of derivatives	10,031	3,428	4,845
Income tax expense	745,654	436,038	519,480
Expense related to defined benefit plan	127,696	118,143	110,021
Share option	414
Depreciation and amortization	3,247,519	3,068,558	2,993,486
Bad debt expense	34,584	37,820	60,450
Loss on disposal of property and equipment and intangible assets	60,086	63,797	21,392
Impairment loss on property and equipment and intangible assets	54,946	24,506	35,845
Loss relating to financial liabilities at fair value through profit or loss	678	4,018	526
Bad debt for accounts receivable - other	5,793	40,312	15,323
Loss on impairment of investment assets	9,003	24,033	42,966
Other expenses	46,353	30,685	4,845
Adjustments for income and expenses from operating activities	₩ 2,096,764	₩ 3,039,561	₩ 3,250,143

XML

Statements of Cash Flows - Changes in Assets and Liabilities from Operating Activities (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Adjustments to reconcile profit (loss) [abstract]
Accounts receivable - trade	₩ 46,144	₩ 88,549	₩ 7,554
Accounts receivable - other	(159,960)	(446,286)	(11,108)
Accrued income	14	445	116
Advance payments	(1,269)	47,615	(35,906)
Prepaid expenses	(28,362)	(30,311)	(40,464)
Value-Added Tax refundable	(3,080)	(4,587)	1,385
Inventories	(17,958)	798	(7,814)
Long-term accounts receivable - other	(137,979)	(147,117)
Guarantee deposits	14,696	4,844	(11,238)
Accounts payable - trade	(26,151)	75,585	12,442
Accounts payable - other	134,542	316,464	(107,114)
Advanced receipts	(13,470)	37,429	6,421
Withholdings	(13,041)	107,516	(191,209)
Deposits received	(4,916)	(2,153)	(9,661)
Accrued expenses	116,065	173,072	(28,845)
Value-Added Tax payable	7,505	(4,072)	3,494
Unearned revenue	(339)	(36,209)	(115,187)
Provisions	(20,488)	20,235	(30,562)
Long-term provisions	(2,449)	4,115	(4,447)
Plan assets	(95,828)	(125,440)	(67,831)
Retirement benefit payment	(60,883)	(55,350)	(58,513)
Others	5,739	(11,378)	2,753
Changes in assets and liabilities from operating activities	₩ (261,468)	₩ 13,764	₩ (685,734)

XML

Statements of Cash Flows - Significant Non-cash Transactions (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Non-cash Investing and Financing Transactions [Abstract]
Increase of accounts payable - other related to acquisition of property and equipment and intangible assets	₩ 44,214	₩ 1,511,913	₩ 39,973

XML

Statements of Cash Flows - Reconciliation of Liabilities Arising from Financing Activities (Detail) ₩ in Millions	12 Months Ended
	Dec. 31, 2017 KRW (₩)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	₩ 9,160,134
Cash flows	(65,314)
Exchange rate changes	(239,151)
Fair value changes	(968)
Other changes	41,641
Ending balance	8,896,342
Short-term borrowings [Member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	2,614
Cash flows	127,386
Ending balance	130,000
Long-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	172,906
Cash flows	87,299
Exchange rate changes	(7,898)
Other changes	510
Ending balance	252,817
Debentures [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	7,194,207
Cash flows	130,558
Exchange rate changes	(245,456)
Other changes	6,878
Ending balance	7,086,187
Long-term payables - other [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	1,918,024
Cash flows	(305,476)
Other changes	28,533
Ending balance	1,641,081
Derivative financial liabilities [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	87,153
Cash flows	(105,269)
Exchange rate changes	13,281
Fair value changes	39,267
Other changes	5,038
Ending balance	39,470
Derivative financial assets [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(214,770)
Cash flows	188
Exchange rate changes	922
Fair value changes	(40,235)
Other changes	682
Ending balance	₩ (253,213)

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Reconciliation of Liabilities Arising from Financing Activities (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of cash flows [abstract]
Payments of cash dividends	₩ (706,091)	₩ (706,091)	₩ (668,494)
Payments of interest on hybrid bond	(16,840)	(16,840)	(16,840)
Transactions with non-controlling interests	(38,373)
Cash flow from other financing activities	(761,304)
Total	₩ (826,618)	₩ (1,044,829)	₩ (964,583)

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Cash Dividends paid to the Parent Company - Summary of Cash Dividends Received from Consolidated Subsidiaries and Associates (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of dividends [Line Items]
Cash dividends received	₩ 12,416	₩ 19,161	₩ 16,102
Subsidiaries [member]
Disclosure of dividends [Line Items]
Cash dividends received		15,693
Associates [member]
Disclosure of dividends [Line Items]
Cash dividends received	89,063	79,132	46,390
Parent [member]
Disclosure of dividends [Line Items]
Cash dividends received	₩ 89,063	₩ 94,825	₩ 46,390