Segment Information (Total Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 17,108	$ 13,835
Operating Segments [Member] | Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,153	1,923
Operating Segments [Member] | Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	11,655	10,680
Corporate and other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,300	$ 1,232