Derivative Instrument Fair Values in the Condensed Consolidated Balance Sheets (Detail) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Designated as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Accrued liabilities	$ 2,264	$ (6,214)
Derivatives not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Accrued liabilities	$ 200	$ 345