Derivative Financial Instruments - Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivatives Fair Value [Line Items]
Asset derivatives fair value		$ 1,200
Liability derivatives fair value		32,400
Derivatives Designated as Hedges [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	$ 1,096	1,189
Liability derivatives fair value	48,326	48,101
Derivatives Designated as Hedges [Member] | Accrued Liabilities [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	42,049	32,431
Derivatives Designated as Hedges [Member] | Other current assets [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	1,096	1,173
Derivatives Designated as Hedges [Member] | Other assets [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value		16
Derivatives Designated as Hedges [Member] | Other liabilities [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	$ 6,277	$ 15,670