XML 129 R114.htm IDEA: XBRL DOCUMENT
v3.20.4

Segment and Geographic Information (Narrative) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2020 Segment plant customer | Dec. 31, 2019 customer | Dec. 31, 2018 customer
Segment Reporting Information [Line Items] |  |  |
Number of segments | Segment | 2 |  |
Number of Building Product Facilities | plant | 37 |  |
Olefins [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Number of major customers | 0 | 0 | 0
Vinyls [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Number of major customers | 0 | 0 | 0

X
- 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_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Concentration Risk, Number of Major Customers + References No definition available. + Details
Name: | wlk_ConcentrationRiskNumberOfMajorCustomers
Namespace Prefix: | wlk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of company plants that manufacture building products. + References No definition available. + Details
Name: | wlk_NumberOfPlants
Namespace Prefix: | wlk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of segments + References No definition available. + Details
Name: | wlk_NumberOfSegments
Namespace Prefix: | wlk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wlk_OlefinsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wlk_VinylsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |