Derivative Financial Instruments - Impact of Derivatives on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 65,116	$ 15,314
Derivative Liabilities	(60,892)	(30,497)
Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	65,116	15,314
Derivative Liabilities	(60,892)	(30,497)
Total net derivatives	4,224	(15,183)
Interest rate swaps | Trading
Derivatives, Fair Value [Line Items]
Derivative Assets	1,745	83
Derivative Liabilities	0	(646)
Total net derivatives	1,745	(563)
Interest rate swaps | Cash Flow | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Derivative Liabilities	(60,892)	(27,512)
Total net derivatives	(60,892)	(27,512)
Interest rate swaps | Fair Value | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets	63,371	15,231
Derivative Liabilities	0	(2,339)
Total net derivatives	$ 63,371	$ 12,892