Derivative Financial Instruments - Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Asset derivatives fair value		$ 1,200
Liability derivatives fair value		32,400
Derivatives Designated as Hedges [Member]
Derivative [Line Items]
Asset derivatives fair value	$ 1,459	1,189
Liability derivatives fair value	46,912	48,101
Derivatives Designated as Hedges [Member] | Other current assets [Member]
Derivative [Line Items]
Asset derivatives fair value	1,332	1,173
Derivatives Designated as Hedges [Member] | Other assets [Member]
Derivative [Line Items]
Asset derivatives fair value	127	16
Derivatives Designated as Hedges [Member] | Accrued Liabilities [Member]
Derivative [Line Items]
Liability derivatives fair value	40,064	32,431
Derivatives Designated as Hedges [Member] | Other liabilities [Member]
Derivative [Line Items]
Liability derivatives fair value	$ 6,848	$ 15,670