Derivative Financial Instruments - Summary of Derivative Activity and Related Impact on Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	$ (842)	$ 20,404
Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Interest expense—borrowings
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	609	638
Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Net (losses) gains on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(17)	(3)
Derivatives designated as hedging instruments | Interest rate risks | Interest Rate Risk
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	592	635
Derivatives not designated as hedging instruments | Currency exchange risks
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	283	(141)
Derivatives not designated as hedging instruments | Currency exchange risks | Loans | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	2,491	(20,159)
Derivatives not designated as hedging instruments | Currency exchange risks | Foreign exchange forwards | Net (losses) gains on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(2,208)	20,018
Derivatives not designated as hedging instruments | Other derivative instruments | Other derivative contracts | Net (losses) gains on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(421)	(57)
Derivatives not designated as hedging instruments | Other derivative instruments | Foreign exchange forwards
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(2,001)	117
Derivatives not designated as hedging instruments | Other derivative instruments | Foreign exchange forwards | Net (losses) gains on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(5,654)	(507)
Derivatives not designated as hedging instruments | Other derivative instruments | Foreign exchange forwards | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	3,653	624
Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant assets | Net (losses) gains on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	$ 6,605	$ 20,278