Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-Subparagraph e

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt amount in excess of guaranteed by subsidiaries.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Maturity

+ References

No definition available.

+ Details

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Namespace Prefix:	wlk_
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Balance Type:	na
Period Type:	duration

- Definition

Represents repurchase price, of deb instrument, as percentage of principal amount upon change of control and below investment grade rating event

+ References

No definition available.

+ Details

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- Definition

Maximum number of days from change of control for below investment grade rating event.

+ References

No definition available.

+ Details

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Long-Term Debt (Senior Notes Due 2022) (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended
	Jul. 17, 2012	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2012
Debt Instrument [Line Items]
Stated interest rate		6.50%
3.60% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Senior notes, principal amount issued	$ 250,000
Stated interest rate	3.60%	3.60%	3.60%	3.60%
Maturity	2022	2022
Senior notes, original discount issue	1,183
Senior notes, repurchase price as percentage of principal amount upon change of control and below investment grade rating event		101.00%
Senior notes, maximum number of days from change of control for below investment grade rating event		60 days
Senior notes, minimum debt amount guaranteed by subsidiaries		$ 5,000
3.60% Senior Notes Due 2022 [Member] \| Prior to April Fifteenth Twenty Twenty Two
Debt Instrument [Line Items]
Senior notes, redemption price as percentage of principal amount		100.00%
3.60% Senior Notes Due 2022 [Member] \| On or After April Fifteenth Twenty Twenty Two
Debt Instrument [Line Items]
Senior notes, redemption price as percentage of principal amount		100.00%