Derivatives and Hedging Activities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019 USD ($) Derivative	Dec. 31, 2018 USD ($) Derivative	Dec. 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount	$ 399,900,000	$ 229,800,000
Net gain (loss) on change in fair value	(2,536,000)	$ 131,000	$ (196,000)
Collateral posted with market value on liability positions with credit risk-related contingent features	$ 33,700,000
Interest Rate Swaps [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps | Derivative	65	43
Net gain (loss) on change in fair value	$ (1,100,000)	$ (400,000)	(400,000)
Income (loss) on derivative instrument not designated hedges	$ 4,500,000	$ 2,100,000	$ 2,300,000