Derivatives - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) Derivatives	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Derivatives	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	$ 0	$ 221
Derivative, Gain (Loss) on Derivative, Net	$ (45)	0	$ (88)	$ 789
Risk Participation Agreements Purchased [Domain]
Risk participation Agreements [Line Items]
Number of interest rate swaps | Derivatives	35		35
Risk Participation Agreements Sold [Domain]
Risk participation Agreements [Line Items]
Number of interest rate swaps | Derivatives	12		12
Forward Contracts [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	$ 0	125	$ 0	96
Derivative Liability, Cost Basis, Gross Asset	23,400		23,400		$ 6,900
Derivative Liability, Fair Value, Gross Asset	24,800		24,800		7,600
Derivative Liability, Notional Amount, Gross Asset	32,700		32,700		9,900
Derivative, Gain (Loss) on Derivative, Net	12		500
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	48		48		170
Derivative, Notional Amount	47,000		47,000		15,000
Derivative, Gain (Loss) on Derivative, Net	201	0	122	0
Interest Rate Contract [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)			0	(432)
Foreign Exchange [Member]
Risk participation Agreements [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	3	2	4	10
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	(50)		(50)		6
Derivative, Notional Amount	4,874		4,874		1,927
Derivative Liability, Cost Basis, Gross Asset	4,900		4,900		1,900
Derivative Liability, Fair Value, Gross Asset	4,800		4,800		1,900
Interest Rate Swap [Member]
Risk participation Agreements [Line Items]
Derivative Instruments Designated As Hedging Instruments Interest Income	0	(193)	(118)	(424)
Derivative Instruments Designated As Hedging Instruments Interest Expense	(70)	0	(70)	0
Derivative, Net Hedge Ineffectiveness Gain (Loss)	0	$ 0	7	$ 10
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Fair Value, Net	124		124		133
Derivative, Notional Amount	70,000		70,000		$ 65,000
2024 [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Notional Amount	30,000		30,000
2026 [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Risk participation Agreements [Line Items]
Derivative, Notional Amount	$ 40,000		$ 40,000