Other Assets (Additional Information) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other Assets [Line Items]
Amortization expense on intangible assets, included in other assets	$ 9,283	$ 8,634	$ 26,566	$ 21,392
Olefins
Other Assets [Line Items]
Goodwill	29,990		29,990
Vinyls
Other Assets [Line Items]
Goodwill	$ 32,026		$ 32,026