Summary of Fair Value of Derivative Assets and Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair value	$ 23,745	$ 12,303
Liability Derivatives, Fair value	31,858	12,258
Derivatives not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair value	23,199	11,700
Liability Derivatives, Fair value	24,212	11,921
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair value	546	603
Liability Derivatives, Fair value	$ 7,646	$ 337