Information Relate to Effect of Derivative Instruments on Our Consolidated Income Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 155	$ (985)	$ (1,538)	$ (792)
Revaluation Of Derivatives | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	581	(2,036)	(694)	(2,514)
Revaluation Of Derivatives | Currency Related Swap
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(364)	1,045	1,895	1,315
Revaluation Of Derivatives | Commodity derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives		(2)		143
Foreign Currency Gain (Loss) | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(426)	1,051	(844)	1,722
Interest Expense | Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	8	(12)	8	(54)
Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 30	$ (25)	$ 105	$ (55)