Derivatives and Hedging Activities - Summary of Effect of Derivative Instruments on Income Statement (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	$ (2,536)	$ 131	$ (196)
Interest Rate Swaps [Member] | Other Income [Member]
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	(1,101)	(437)	(391)
Interest Rate Loan Commitments [Member] | Mortgage Banking Income [Member]
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	(81)	125	172
Forward TBA Contracts [Member] | Mortgage Banking Income [Member]
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	$ (1,354)	$ 443	$ 23