Segment Information (Total Assets) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,544,174	$ 3,266,821
Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,355,157	1,441,752
Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	956,665	824,825
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,232,352	$ 1,000,244