Derivatives - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Derivatives	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Derivatives	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Risk participation Agreements [Line Items]
HedgedItemsOfCashFlowHedge	$ 150,000		$ 150,000
Derivative Instruments Designated As Hedging Instruments Interest Income		$ 404
Derivative, Net Hedge Ineffectiveness Gain (Loss)	$ 9	16
Risk Participation Agreements Purchased [Domain]
Risk participation Agreements [Line Items]
Number of interest rate swaps | Derivatives	32		32
Risk Participation Agreements Sold [Domain]
Risk participation Agreements [Line Items]
Number of interest rate swaps | Derivatives	8		8
Forward Contracts [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	$ 61	0	$ (34)	$ 0
Derivative Liability, Cost Basis, Gross Asset	13,800		13,800
Derivative Liability, Fair Value, Gross Asset	14,300		14,300
Derivative Liability, Notional Amount, Gross Asset	23,300		23,300
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	34		34		$ 0
Derivative, Notional Amount	28,000		28,000		0
Foreign Exchange [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	2	$ 7	3	14
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	(4)		(4)		8
Derivative, Notional Amount	7,785		7,785		4,749
Derivative Liability, Cost Basis, Gross Asset	7,800		7,800		4,700
Derivative Liability, Fair Value, Gross Asset	7,800		7,800		4,700
Three Year Maturity [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Notional Amount	35,000		35,000
Four Year Maturity [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Notional Amount	115,000		115,000
Interest Rate Swap [Member]
Risk participation Agreements [Line Items]
Derivative Instruments Designated As Hedging Instruments Interest Income	35		420	1,258
Derivative, Net Hedge Ineffectiveness Gain (Loss)			82	$ 57
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	189		189		443
Derivative, Notional Amount	$ 150,000		$ 150,000		$ 200,000