Segment Information (Total Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,524,405	$ 5,213,990
Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,817,303	1,785,895
Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,601,263	2,618,646
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,105,839	$ 809,449