Information Relate to Effect of Derivative Instruments on Our Consolidated Income Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ (428)	$ (1,791)	$ (1,693)	$ 193
Revaluation Of Derivatives | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(301)	(1,565)	(1,275)	(478)
Revaluation Of Derivatives | Currency Related Swap
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	940	123	2,260	270
Revaluation Of Derivatives | Commodity derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives		19		145
Foreign Currency Gain (Loss) | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(127)	(226)	(418)	671
Interest Expense | Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	2	(14)	2	(42)
Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 36	$ 3	$ 75	$ (30)