Derivative Financial Instruments - Summary of Derivative Activity and Related Impact on Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives			$ (8,505)	$ 1,636
Equity warrant assets
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives			9,053	1,803
Derivatives designated as hedging instruments | Interest rate risks
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 375	$ 577	928	1,169
Derivatives designated as hedging instruments | Interest rate risks | Interest expense—borrowings
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	381	590	935	1,199
Derivatives designated as hedging instruments | Interest rate risks | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	(6)	(13)	(7)	(30)
Derivatives not designated as hedging instruments | Foreign Exchange Contract
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	42	(1,384)	905	(1,101)
Derivatives not designated as hedging instruments | Foreign Exchange Contract | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	(14,554)	3,923	(17,799)	1,715
Derivatives not designated as hedging instruments | Foreign Exchange Contract | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	14,596	(5,307)	18,704	(2,816)
Derivatives not designated as hedging instruments | Other derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	185	(65)	650	(2,065)
Derivatives not designated as hedging instruments | Other derivative instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	(2,190)	68	(4,479)	(5,586)
Derivatives not designated as hedging instruments | Other derivative instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	2,375	(133)	5,129	3,521
Derivatives not designated as hedging instruments | Other derivative instruments | Other derivative contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	(210)	(269)	(486)	(690)
Derivatives not designated as hedging instruments | Equity warrant assets | gains and losses on equity warrant assets [Domain]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 10,820	$ 5,089	$ 17,510	$ 11,695