Summary of Significant Accounting Policies - Summary of measuring lease liabilities (Details) - KRW (₩) ₩ in Millions		12 Months Ended
Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018
Lease liabilities [abstract]
Operating Lease Commitments	₩ 119,659
Lease Commitments Discounted	115,614
Recognition exemption for lease of low-value assets	(262)	₩ (1,188)
Recognition exemption for leases with less than 12 months of lease term at adoption	(233)	(1,783)
Lease liabilities	₩ 115,119	₩ 88,512	₩ 115,119

The amount of the expense relating to leases of low-value assets accounted for applying paragraph 6 of IFRS 16. This expense shall not include the expense relating to short-term leases of low-value assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2019-01-01
-Paragraph 53
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_53_d&doctype=Standard
-URIDate 2019-03-27

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of the expense relating to short-term leases accounted for applying paragraph 6 of IFRS 16. This expense need not include the expense relating to leases with a lease term of one month or less. Short-term lease is a lease that, at the commencement date, has a lease term of 12 months or less. A lease that contains a purchase option is not a short-term lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2019-01-01
-Paragraph 53
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_53_c&doctype=Standard
-URIDate 2019-03-27

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of liabilities related to the entity's leases. Lease is a contract, or part of a contract, that conveys the right to use an underlying asset for a period of time in exchange for consideration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2019-01-01
-Paragraph 47
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_47_b&doctype=Standard
-URIDate 2019-03-27

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Lease commitments discounted.

+ References

No definition available.

+ Details

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Namespace Prefix:	lpl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating lease commitments.

+ References

No definition available.

+ Details

Name:	lpl_OperatingLeaseCommitments
Namespace Prefix:	lpl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant