Total Assets (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,441,938	$ 3,266,821
Olefins
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,371,679	1,441,752
Vinyls
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	905,699	824,825
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,164,560	$ 1,000,244