Supplemental Information (Equity Method Investments) (Details) - LACC, LLC $ in Millions	3 Months Ended
Mar. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	3.20%
Equity Method Investments Activity [Roll Forward]
Beginning balance	$ 943
Cash contributions	7
Increase in equity method investment	89
Depreciation and amortization	(8)
Ending balance	$ 1,031

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of the investment at close of period. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(3))
-URI http://asc.fasb.org/extlink&oid=122147990&loc=d3e611322-123010

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(2))
-URI http://asc.fasb.org/extlink&oid=122147990&loc=d3e611322-123010

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(Column E))
-URI http://asc.fasb.org/extlink&oid=122147990&loc=d3e611322-123010

+ Details

Name:	us-gaap_InvestmentsInAndAdvancesToAffiliatesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Gross additions to the investment in and advance to the affiliate.

+ References

+ Details

Name:	us-gaap_InvestmentsInAndAdvancesToAffiliatesAtFairValueGrossAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Gross reductions to the investment in and advance to the affiliate.

+ References

+ Details

Name:	us-gaap_InvestmentsInAndAdvancesToAffiliatesAtFairValueGrossReductions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity Method Investments Activity

+ References

No definition available.

+ Details

Name:	wlk_EquityMethodInvestmentsActivityRollForward
Namespace Prefix:	wlk_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the cost of additional investments for under the equity method of accounting.

+ References

No definition available.

+ Details

Name:	wlk_IncreaseinEquityMethodInvestment
Namespace Prefix:	wlk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=wlk_LACCLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: