Derivatives and Hedging Activities - Summary of Effect of Derivative Instruments on Income Statement (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	$ 6,263	$ (5,553)
Interest Rate Swaps [Member] | Other Income [Member]
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	2,761	(2,751)
Interest Rate Loan Commitments [Member] | Mortgage Banking Income [Member]
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	(1,016)	(145)
Forward TBA Contracts [Member] | Mortgage Banking Income [Member]
Derivatives, Fair Value [Line Items]
Total gain (loss) on derivative financial instruments	$ 4,518	$ (2,657)