Derivative Financial Instruments - Total Notional or Contractual Amounts, Fair Value, Collateral and Net Exposure of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Fair Value, Net Total	$ 137,353	$ 126,879
Net Exposure, Net	133,597	119,098
Collateral	3,756	7,781
Derivatives designated as hedging instruments | Interest rate risks | Other assets | Interest rate swaps
Derivative [Line Items]
Notional or Contractual Amount	45,964	45,964
Fair Value, Assets	3,485	4,609
Net Exposure, Assets	3,485	1,639
Collateral	0	2,970
Derivatives not designated as hedging instruments | Currency exchange risks
Derivative [Line Items]
Fair Value, Net exposure	(481)	4,561
Net Exposure, Net	(481)	2,120
Collateral	0	2,441
Derivatives not designated as hedging instruments | Currency exchange risks | Other assets | Foreign exchange forwards
Derivative [Line Items]
Notional or Contractual Amount	17,038	200,957
Fair Value, Assets	594	5,050
Net Exposure, Assets	594	2,609
Collateral	0	2,441
Derivatives not designated as hedging instruments | Currency exchange risks | Other liability | Foreign exchange forwards
Derivative [Line Items]
Notional or Contractual Amount	37,609	6,226
Fair value, Liabilities	(1,075)	(489)
Net Exposure, Liabilities	(1,075)	(489)
Collateral	0	0
Derivatives not designated as hedging instruments | Other derivative instruments | Other derivatives
Derivative [Line Items]
Fair Value, Net exposure	4,258	1,105
Net Exposure, Net	502	(1,265)
Collateral	3,756	2,370
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Equity warrant assets
Derivative [Line Items]
Notional or Contractual Amount	208,270	197,878
Fair Value, Assets	130,091	116,604
Net Exposure, Assets	130,091	116,604
Collateral	0	0
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Other derivatives | Foreign exchange forwards
Derivative [Line Items]
Notional or Contractual Amount	733,204	801,487
Fair Value, Assets	32,431	28,954
Net Exposure, Assets	28,675	26,584
Collateral	3,756	2,370
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Other derivatives | Client foreign currency options
Derivative [Line Items]
Notional or Contractual Amount	28,390	34,926
Fair Value, Assets	246	227
Net Exposure, Assets	246	227
Collateral	0	0
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Other derivatives | Client interest rate derivatives
Derivative [Line Items]
Notional or Contractual Amount	459,614	387,410
Fair Value, Assets	5,164	2,546
Net Exposure, Assets	5,164	2,546
Collateral	0	0
Derivatives not designated as hedging instruments | Other derivative instruments | Other liability | Other derivatives | Foreign exchange forwards
Derivative [Line Items]
Notional or Contractual Amount	695,403	774,355
Fair value, Liabilities	(27,618)	(27,647)
Net Exposure, Liabilities	(27,618)	(27,647)
Collateral	0	0
Derivatives not designated as hedging instruments | Other derivative instruments | Other liability | Other derivatives | Client foreign currency options
Derivative [Line Items]
Notional or Contractual Amount	28,390	34,926
Fair value, Liabilities	(246)	(227)
Net Exposure, Liabilities	(246)	(227)
Collateral	0	0
Derivatives not designated as hedging instruments | Other derivative instruments | Other liability | Other derivatives | Client interest rate derivatives
Derivative [Line Items]
Notional or Contractual Amount	459,614	387,410
Fair value, Liabilities	(5,719)	(2,748)
Net Exposure, Liabilities	(5,719)	(2,748)
Collateral	$ 0	$ 0