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Acquisitions - Narrative (Details) - USD ($) $ in Millions					9 Months Ended
Acquisitions - Narrative (Details) - USD ($) $ in Millions	Feb. 01, 2022	Oct. 01, 2021	Sep. 10, 2021	Aug. 19, 2021	Sep. 30, 2022
Business Acquisition [Line Items]
Measurement period adjustments					$ 25
Goodwill acquired during the period					119
Hexion
Business Acquisition [Line Items]
Total Westlake Corporation purchase consideration	$ 1,207
Acquisition related costs					$ 6
Measurement period adjustments	9
Acquired net sales	1,146
Acquired net income	68
Intangible assets	145
Goodwill acquired during the period	$ 128
Hexion \| Trade Names
Business Acquisition [Line Items]
Finite-lived intangible asset useful life	19 years
Hexion \| Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset useful life	11 years
Hexion \| Technology-Based Intangible Assets
Business Acquisition [Line Items]
Finite-lived intangible asset useful life	17 years
Boral Target Companies
Business Acquisition [Line Items]
Total Westlake Corporation purchase consideration		$ 2,140
Measurement period adjustments		16
Intangible assets		952
Customer relationships		645
Goodwill acquired during the period		$ 787
Lasco Fittings, Inc.
Business Acquisition [Line Items]
Total Westlake Corporation purchase consideration				$ 277
Intangible assets				77
Goodwill acquired during the period				105
Lasco Fittings, Inc. \| Customer Relationships
Business Acquisition [Line Items]
Intangible assets				$ 50
Dimex, LLC
Business Acquisition [Line Items]
Total Westlake Corporation purchase consideration			$ 172
Intangible assets			72
Goodwill acquired during the period			68
Dimex, LLC \| Customer Relationships
Business Acquisition [Line Items]
Intangible assets			$ 48
Minimum \| Boral Target Companies \| Customer Relationships
Business Acquisition [Line Items]
Intangible assets useful life		12 years
Minimum \| Lasco Fittings, Inc.
Business Acquisition [Line Items]
Finite-lived intangible asset useful life				17 years
Minimum \| Dimex, LLC
Business Acquisition [Line Items]
Finite-lived intangible asset useful life			17 years
Maximum \| Boral Target Companies \| Customer Relationships
Business Acquisition [Line Items]
Intangible assets useful life		22 years
Maximum \| Lasco Fittings, Inc.
Business Acquisition [Line Items]
Finite-lived intangible asset useful life				18 years
Maximum \| Dimex, LLC
Business Acquisition [Line Items]
Finite-lived intangible asset useful life			19 years