Segment and Geographic Information (Total Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 11,602	$ 12,076
Operating Segments [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Total assets	2,024	2,006
Operating Segments [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Total assets	8,879	8,853
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 699	$ 1,217