Derivative Financial Instruments - Summary of Derivative Activity and Related Impact on Consolidated Statements of Income (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		$ (3,887)	$ (3,159)
Gains and losses on equity warrant assets	[1]	6,690	6,606
Equity warrant assets
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		1,545	2,317
Derivatives designated as hedging instruments | Interest rate risks
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		553	592
Derivatives designated as hedging instruments | Interest rate risks | Interest expense—borrowings
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		554	609
Derivatives designated as hedging instruments | Interest rate risks | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		(1)	(17)
Derivatives not designated as hedging instruments | Foreign Exchange Contract
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		863	283
Derivatives not designated as hedging instruments | Foreign Exchange Contract | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		(3,245)	(2,208)
Derivatives not designated as hedging instruments | Foreign Exchange Contract | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		4,108	2,491
Derivatives not designated as hedging instruments | Other derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		465	(2,001)
Derivatives not designated as hedging instruments | Other derivative instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		(2,289)	(5,654)
Derivatives not designated as hedging instruments | Other derivative instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		2,754	3,653
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		(276)	(421)
Derivatives not designated as hedging instruments | Equity warrant assets | gains and losses on equity warrant assets [Domain]
Derivative Instruments, Gain (Loss) [Line Items]
Gains and losses on equity warrant assets		$ 6,690	$ 6,607

[1] Our consolidated statements of income were modified from prior period's presentation to conform to the current period's presentation, which reflects a new line item to separately disclose net gains on equity warrant assets. In prior periods, net gains on equity warrant assets were reported as a component of gains on derivative instruments, net. We removed the line item gains on derivative instruments, net and reclassified all other gains on derivative instruments, net to other noninterest income.