Derivatives - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) Derivatives	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Risk participation Agreements [Line Items]
HedgedItemsOfCashFlowHedge	$ 115,000
Risk Participation Agreements Purchased [Domain]
Risk participation Agreements [Line Items]
Number of interest rate swaps | Derivatives	37
Risk Participation Agreements Sold [Domain]
Risk participation Agreements [Line Items]
Number of interest rate swaps | Derivatives	12
Forward Contracts [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	$ (62)	$ 112
Derivative Liability, Cost Basis, Gross Asset	7,000		$ 14,300
Derivative Liability, Fair Value, Gross Asset	7,200		14,700
Derivative Liability, Notional Amount, Gross Asset	18,300		13,800
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	(81)		(19)
Derivative, Notional Amount	22,000		17,000
Foreign Exchange [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	(3)	2
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	13		70
Derivative, Notional Amount	7,858		10,077
Derivative Liability, Cost Basis, Gross Asset	7,800		10,000
Derivative Liability, Fair Value, Gross Asset	7,800		10,100
Interest Rate Swap [Member]
Risk participation Agreements [Line Items]
Derivative Instruments Designated As Hedging Instruments Interest Income	(81)	249
Derivative, Net Hedge Ineffectiveness Gain (Loss)	0	$ 78
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	590		(459)
Derivative, Notional Amount	$ 115,000		$ 150,000