Derivatives - Credit Value Adjustment Recorded Related to Notional Amount of Derivatives Outstanding (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	$ (366)	$ (317)
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	(311,748)	(345,102)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	(189)	(443)
Derivative, Notional Amount	(150,000)	(200,000)
Interest Rate Cap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	(36,500)	(14,762)
Credit Default Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	(188,854)	(174,213)
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	(34)	0
Derivative, Notional Amount	(28,000)	0
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	4	(8)
Derivative, Notional Amount	(7,785)	(4,749)
Short [Member] | Credit Default Swap, Selling Protection [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ (39,464)	$ (40,281)