Fair Value of Financial Instruments - Fair Value of Gross Position of Derivative Contracts in Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives (Assets)/ liabilities as hedging instruments	$ 5,979	$ 349
Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivatives (Assets)/ liabilities as hedging instruments	5,979	470
Designated as Hedging Instruments [Member] | Gross Amounts Recognized [Member]
Derivatives, Fair Value [Line Items]
Derivatives (Assets)/ liabilities as hedging instruments	6,483	2,702
Designated as Hedging Instruments [Member] | Gross Amounts Offset [Member]
Derivatives, Fair Value [Line Items]
Derivatives (Assets)/ liabilities as hedging instruments	(504)	(2,232)
Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivatives (Assets)/ liabilities as hedging instruments		(121)
Not Designated as Hedging Instruments [Member] | Gross Amounts Recognized [Member]
Derivatives, Fair Value [Line Items]
Derivatives (Assets)/ liabilities as hedging instruments		$ (121)