Derivative Financial Instruments - Total Notional or Contractual Amounts, Fair Value, Collateral and Net Exposure of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Fair Value, Net Total	$ 147,640	$ 145,632
Collateral	4,840	12,668
Net Exposure, Net	142,800	132,964
Interest rate swaps
Derivative [Line Items]
Fair value, Assets		810
Foreign exchange forwards
Derivative [Line Items]
Fair value, Assets	93,857	57,644
Fair value, Liabilities	(87,871)	(44,285)
Client foreign currency options
Derivative [Line Items]
Fair value, Assets	1,090	10,383
Fair value, Liabilities	(1,090)	(10,383)
Client interest rate derivatives
Derivative [Line Items]
Fair value, Assets	11,824	10,110
Fair value, Liabilities	(11,955)	(9,770)
Derivatives designated as hedging instruments | Interest rate risks | Other assets
Derivative [Line Items]
Derivative, Notional Amount		45,964
Fair value, Assets		810
Collateral		89
Net Exposure, Assets		721
Derivatives not designated as hedging instruments | Foreign Exchange Contract
Derivative [Line Items]
Fair Value, Net exposure	1,922	2,089
Collateral	0	0
Net Exposure, Net	1,922	2,089
Derivatives not designated as hedging instruments | Foreign Exchange Contract | Other assets
Derivative [Line Items]
Derivative, Notional Amount	286,378	219,950
Fair value, Assets	3,166	3,057
Collateral	0	0
Net Exposure, Assets	3,166	3,057
Derivatives not designated as hedging instruments | Foreign Exchange Contract | Other liability
Derivative [Line Items]
Derivative, Notional Amount	84,618	54,338
Fair value, Liabilities	(1,244)	(968)
Collateral	0	0
Net Exposure, Liabilities	(1,244)	(968)
Derivatives not designated as hedging instruments | Other derivative instruments | Other derivative contracts
Derivative [Line Items]
Fair Value, Net exposure	3,933	11,610
Collateral	4,840	12,579
Net Exposure, Net	(907)	(969)
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets
Derivative [Line Items]
Net Exposure, Assets	141,785	131,123
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Other derivative contracts
Derivative [Line Items]
Derivative, Notional Amount	101,544	775,000
Fair value, Assets	1,090	10,383
Collateral	0	0
Net Exposure, Assets	1,090	10,383
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Client interest rate derivatives
Derivative [Line Items]
Derivative, Notional Amount	676,148	583,511
Fair value, Assets	11,824	10,110
Collateral	0	0
Net Exposure, Assets	11,824	10,110
Derivatives not designated as hedging instruments | Other derivative instruments | Other assets | Foreign Exchange Contract
Derivative [Line Items]
Derivative, Notional Amount	1,925,726	1,251,308
Fair value, Assets	90,691	54,587
Collateral	4,840	12,579
Net Exposure, Assets	85,851	42,008
Derivatives not designated as hedging instruments | Other derivative instruments | Other liability | Other derivative contracts
Derivative [Line Items]
Derivative, Notional Amount	101,544	775,000
Fair value, Liabilities	(1,090)	(10,383)
Collateral	0	0
Net Exposure, Liabilities	(1,090)	(10,383)
Derivatives not designated as hedging instruments | Other derivative instruments | Other liability | Client interest rate derivatives
Derivative [Line Items]
Derivative, Notional Amount	711,969	627,639
Fair value, Liabilities	(11,955)	(9,770)
Collateral	0	0
Net Exposure, Liabilities	(11,955)	(9,770)
Derivatives not designated as hedging instruments | Other derivative instruments | Other liability | Foreign Exchange Contract
Derivative [Line Items]
Derivative, Notional Amount	1,838,439	1,068,991
Fair value, Liabilities	(86,627)	(43,317)
Collateral	0	0
Net Exposure, Liabilities	$ (86,627)	$ (43,317)