Derivatives, Hedging Activities and Other Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Fair value of swaps at inception	$ 0
Expense in fair value adjustments	3	$ 1
Amount of collateral posted with third party	12,700		$ 13,800
Aggregate fair value of derivative financial instruments in liability position	1,700		2,000
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of customer-initiated interest rate	1,679		2,087
Risk Participation Agreement [Member]
Derivatives, Fair Value [Line Items]
Derivative contracts for an upfront fee	243
Risk Participation Agreement [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional amount	17,800
Fair value of customer-initiated interest rate	3
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional amount	$ 1,400		$ 1,500
Interest payment description	For each of these swap agreements, the floating rate is based on the one-month London Interbank Offered Rate (“LIBOR”) paid on the first day of the month which matches the interest payment date on each subordinated note.
Minimum [Member]
Derivatives, Fair Value [Line Items]
Expiration dates for swap agreements, range	Mar. 01, 2017
Maximum [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Expiration dates for swap agreements, range	Aug. 01, 2022