Derivatives and Hedging Activities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020 USD ($) Derivative	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) Derivative
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net gain (loss) on change in fair value	$ (5,553,000)	$ (616,000)
Collateral posted with market value on liability positions with credit risk-related contingent features	$ 77,700,000
Interest Rate Swaps [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps | Derivative	73		65
Notional or contractual amount	$ 535,500,000		$ 399,900,000
Net gain (loss) on change in fair value	(2,800,000)	(300,000)
Income (loss) on derivative instrument not designated hedges	2,600,000	700,000
Other Contract [Member] | Forward TBA Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional or contractual amount	140,500,000		$ 50,000,000.0
Net gain (loss) on change in fair value	$ (2,700,000)	$ (300,000)