Balance Sheet Components

Cash, Cash Equivalents and Short-Term and Long-Term Investments

Cash, cash equivalents and short-term and long-term investments consisted of the following as of December 31 (in thousands):



	2018		2017
Cash and cash equivalents:
Cash ⁽¹⁾	$	486,648	$	985,382
Cash equivalents:
Money market funds	119,518		427,135
Total cash and cash equivalents	606,166		1,412,517
Short-term and long-term investments:
Certificates of deposit	2,823		31,351
Publicly traded equity securities	1,717		6,163
Total short-term and long-term investments	4,540		37,514
Total cash, cash equivalents and short-term and long-term investments	$	610,706	$	1,450,031


⁽¹⁾	Excludes restricted cash.


⁽²⁾	Total unrealized gains on the publicly traded equity securities as of December 31, 2017 were insignificant. The changes in the fair values of publicly traded equity securities were recognized within other income (expense) in the Company's consolidated statements of operations as a result of the adoption of ASU 2016-01 on January 1, 2018.

As of December 31, 2018 and 2017, cash and cash equivalents included investments which were readily convertible to cash and had original maturity dates of 90 days or less. The maturities of certificates of deposit classified as short-term investments were one year or less as of December 31, 2018 and 2017. The maturities of certificates of deposits classified as long-term investments were greater than one year and less than three years as of December 31, 2017. The balance of certificates of deposits, by contractual maturity, as of December 31 (in thousands):



	2018		2017
Due within one year	$	2,823	$	28,271
Due after one year through three years	—		3,080
Total	$	2,823	$	31,351

Accounts Receivable

Accounts receivable, net, consisted of the following as of December 31 (in thousands):



	2018			2017
Accounts receivable	$	646,069		$	594,541
Allowance for doubtful accounts	(15,950		)	(18,228		)
Accounts receivable, net	$	630,119		$	576,313

Trade accounts receivable are recorded at the invoiced amount and generally do not bear interest.

The following table summarizes the activity of the Company's allowance for doubtful accounts (in thousands):



Balance as of December 31, 2015	$	10,352
Provision for allowance for doubtful accounts	8,260
Net write-offs	(2,521		)
Impact of foreign currency exchange	(416		)
Balance as of December 31, 2016	15,675
Provision for allowance for doubtful accounts	5,627
Net write-offs	(4,546		)
Impact of foreign currency exchange	1,472
Balance as of December 31, 2017	18,228
Provision for allowance for doubtful accounts	7,236
Net write-offs	(8,396		)
Impact of foreign currency exchange	(1,118		)
Balance as of December 31, 2018	$	15,950

Other Current Assets

Other current assets consisted of the following as of December 31 (in thousands):



	2018		2017
Prepaid expenses	$	70,433	$	64,832
Taxes receivable	98,245		110,961
Restricted cash, current	10,887		26,919
Other receivables	12,611		7,797
Derivative instruments	62,170		4,175
Contract asset, current	9,778		—
Other current assets	10,733		17,343
Total other current assets	$	274,857	$	232,027

Property, Plant and Equipment, Net

Property, plant and equipment, net consisted of the following as of December 31 (in thousands):



	2018			2017
Core systems	$	7,073,912		$	6,334,702
Buildings	4,822,501			3,906,686
Leasehold improvements	1,637,133			1,850,351
Construction in progress	974,152			425,428
Personal property	857,585			798,133
Land	631,367			423,539
	15,996,650			13,738,839
Less accumulated depreciation	(4,970,630		)	(4,344,237		)
Property, plant and equipment, net	$	11,026,020		$	9,394,602

Core systems, buildings, leasehold improvements, personal property and construction in progress recorded under capital leases aggregated to $823.6 million and $760.4 million as of December 31, 2018 and 2017, respectively. As of December 31, 2018 and 2017, the Company recorded accumulated depreciation for assets under capital leases of $248.9 million and $199.2 million, respectively.

Goodwill and Other Intangibles

The following table presents goodwill and other intangible assets, net, for the years ended December 31, 2018 and 2017 (in thousands):



	2018			2017
Goodwill:
Americas	$	1,745,804		$	1,561,512
EMEA	2,474,164			2,610,899
Asia-Pacific	616,420			239,351
	$	4,836,388		$	4,411,762
Intangible assets, net:
Intangible assets - customer relationships	$	2,733,864		$	2,673,886
Intangible assets - trade names	71,778			73,295
Intangible assets - favorable leases	35,969			37,913
Intangible assets - in-place leases	33,671			10,327
Intangible assets - licenses	9,697			9,696
	2,884,979			2,805,117
Accumulated amortization - customer relationships	(467,111		)	(331,930		)
Accumulated amortization - trade names	(62,585		)	(71,728		)
Accumulated amortization - favorable leases	(9,986		)	(9,607		)
Accumulated amortization - in-place leases	(8,118		)	(3,644		)
Accumulated amortization - licenses	(3,883		)	(3,236		)
	(551,683		)	(420,145		)
Total intangible assets, net	$	2,333,296		$	2,384,972

Changes in the carrying amount of goodwill by geographic regions are as follows (in thousands):



	Americas			EMEA			Asia-Pacific			Total
Balance as of December 31, 2016	$	469,438		$	2,281,306		$	235,320		$	2,986,064
Purchase accounting adjustments - Verizon Data Center acquisition	1,095,262			—			—			1,095,262
Purchase accounting adjustments - Other 2017 acquisitions	—			163,993			—			163,993
Impact of foreign currency exchange	(3,188		)	165,600			4,031			166,443
Balance as of December 31, 2017	1,561,512			2,610,899			239,351			4,411,762
Purchase accounting adjustments - Infomart Dallas acquisition	197,378			—			—			197,378
Purchase accounting adjustments - Metronode acquisition	—			—			413,871			413,871
Purchase accounting adjustments - Other acquisitions	333			1,357			—			1,690
Impact of foreign currency exchange	(13,419		)	(138,092		)	(36,802		)	(188,313		)
Balance as of December 31, 2018	$	1,745,804		$	2,474,164		$	616,420		$	4,836,388

Changes in the net book value of intangible assets by geographic regions are as follows (in thousands):



	Americas			EMEA			Asia-Pacific			Total
Balance as of December 31, 2015	$	50,643		$	44,355		$	129,567		$	224,565
TelecityGroup acquisition	—			694,243			—			694,243
Paris IBX Data Center acquisition	—			11,758			—			11,758
Sale of Terra Power	—			—			(2,460		)	(2,460		)
Write-off of intangible asset	(573		)	—			—			(573		)
Amortization of intangibles	(11,348		)	(97,715		)	(13,799		)	(122,862		)
Impact of foreign currency exchange	1,395			(90,280		)	3,445			(85,440		)
Balance as of December 31, 2016	40,117			562,361			116,753			719,231
Verizon Data Center acquisition	1,693,900			—			—			1,693,900
Other 2017 acquisitions	—			112,645			—			112,645
Write-off of intangible asset	—			(725		)	—			(725		)
Amortization of intangibles	(84,749		)	(79,105		)	(13,154		)	(177,008		)
Impact of foreign currency exchange	(2,895		)	36,043			3,781			36,929
Balance as of December 31, 2017	1,646,373			631,219			107,380			2,384,972
Infomart Dallas acquisition	65,847			—			—			65,847
Metronode acquisition	—			—			128,229			128,229
Other acquisitions	—			8,342			—			8,342
Write-off of intangible asset	(334		)	(1,661		)	(3		)	(1,998		)
Amortization of intangibles	(125,683		)	(62,283		)	(15,450		)	(203,416		)
Impact of foreign currency exchange	(7,232		)	(31,757		)	(9,691		)	(48,680		)
Balance as of December 31, 2018	$	1,578,971		$	543,860		$	210,465		$	2,333,296

The Company's goodwill and intangible assets in EMEA, denominated in Euros, British Pounds, Turkish Lira and the United Arab Emirates Dirham, goodwill and intangible assets in Asia-Pacific, denominated in Australian Dollars, Singapore Dollars, Hong Kong Dollars, Japanese Yen and Chinese Yuan, and certain goodwill and intangibles in Americas, denominated in Canadian Dollars, Brazilian Reals and Colombian Pesos, are subject to foreign currency fluctuations. The Company's foreign currency translation gains and losses, including goodwill and intangibles, are a component of other comprehensive income and loss.

Estimated future amortization expense related to these intangibles is as follows (in thousands):



Years ending:
2019	$	199,862
2020	193,073
2021	185,332
2022	181,211
2023	180,883
Thereafter	1,392,935
Total	$	2,333,296

Other Assets

Other assets consisted of the following as of December 31 (in thousands):



	2018		2017
Deferred tax assets, net	$	58,300	$	66,031
Prepaid expenses	125,158		89,784
Debt issuance costs, net	8,532		10,670
Deposits	54,986		48,296
Restricted cash	10,551		11,265
Derivative instruments	10,904		4,110
Contract assets, non-current	16,396		—
Contract costs	188,200		—
Other assets	60,225		11,594
Total other assets	$	533,252	$	241,750

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consisted of the following as of December 31 (in thousands):



	2018		2017
Accounts payable	$	96,980	$	101,744
Accrued compensation and benefits	235,697		214,585
Accrued interest	126,142		100,347
Accrued taxes⁽¹⁾	118,818		130,272
Accrued utilities and security	78,547		68,916
Accrued professional fees	17,010		13,830
Accrued repairs and maintenance	10,736		11,232
Accrued other	72,762		78,331
Total accounts payable and accrued expenses	$	756,692	$	719,257


⁽¹⁾	Includes income taxes payable of $67.9 million and $56.4 million, respectively, as of December 31, 2018 and 2017.

Other Current Liabilities

Other current liabilities consisted of the following as of December 31 (in thousands):



	2018		2017
Deferred revenue, current	$	73,143	$	87,300
Customer deposits	20,430		16,598
Derivative instruments	8,812		34,466
Deferred rent	6,466		6,546
Dividends payable	8,795		11,181
Asset retirement obligations	6,776		1,716
Other current liabilities	2,573		2,107
Total other current liabilities	$	126,995	$	159,914

Other Liabilities

Other liabilities consisted of the following as of December 31 (in thousands):



	2018		2017
Asset retirement obligations	$	89,887	$	96,823
Deferred tax liabilities, net	247,849		252,287
Deferred revenue, non-current	46,641		121,257
Deferred rent	108,693		97,782
Accrued taxes	116,735		64,378
Dividends payable	6,545		6,669
Customer deposits	9,671		10,849
Derivative instruments	928		6,381
Other liabilities	2,814		5,284
Total other liabilities	$	629,763	$	661,710

The following table summarizes the activities of the Company's asset retirement obligation ("ARO") (in thousands):



Asset retirement obligations as of December 31, 2015	$	78,482
Additions	22,955
Adjustments ⁽¹⁾	(2,366		)
Accretion expense	6,685
Impact of foreign currency exchange	(2,741		)
Asset retirement obligations as of December 31, 2016	103,015
Additions	17,736
Adjustments ⁽¹⁾	(34,576		)
Accretion expense	7,335
Impact of foreign currency exchange	5,029
Asset retirement obligations as of December 31, 2017	98,539
Additions	5,126
Adjustments ⁽¹⁾	(11,288		)
Accretion expense	6,285
Impact of foreign currency exchange	(1,999		)
Asset retirement obligations as of December 31, 2018	$	96,663


⁽¹⁾	The ARO adjustments are primarily due to lease amendments and acquisition of real estate assets, as well as other adjustments.