Segment And Geographic Information (Total Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	$ 12,076	$ 10,890
Operating Segments [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Total assets	2,006	2,093
Operating Segments [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Total assets	8,853	8,287
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 1,217	$ 510