Derivative Financial Instruments - Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivatives Fair Value [Line Items]
Asset derivatives fair value		$ 1,000
Liability derivatives fair value		32,000
Derivatives Designated as Hedges [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	$ 1,883	1,189
Liability derivatives fair value	30,667	48,101
Derivatives Designated as Hedges [Member] | Accounts receivable-other [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	1,668	1,173
Derivatives Designated as Hedges [Member] | Accounts payable [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	26,649	32,431
Derivatives Designated as Hedges [Member] | Other assets [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	215	16
Derivatives Designated as Hedges [Member] | Other liabilities [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	$ 4,018	$ 15,670