Derivatives - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Interest rate swap asset	$ 5,838	$ 1,716	[1]
Interest rate swap liability	1,239	2,735	[1]
Cash collateral with counterparties	6,000	6,000
Derivative assets held for sale	144,500	97,100
Mortgage derivative asset	3,456	5,293	[1]
Mortgage derivative liabilities including in other liabilities	0	1,600
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Notional Amount	93,700	154,300
Hedged Instrument [Member]
Derivative [Line Items]
Derivative assets held for sale	$ 241,600	$ 225,000
Identified Hedge [Member]
Derivative [Line Items]
Derivative, fixed interest rate	1.80%
New Hedges [Member] | Minimum [Member]
Derivative [Line Items]
Derivative, fixed interest rate	0.92%
New Hedges [Member] | Maximum [Member]
Derivative [Line Items]
Derivative, fixed interest rate	0.95%
Additional Hedges [Member] | Minimum [Member]
Derivative [Line Items]
Derivative, fixed interest rate	0.83%
Additional Hedges [Member] | Maximum [Member]
Derivative [Line Items]
Derivative, fixed interest rate	0.86%

[1] Derived from audited December 31, 2020 Consolidated Financial Statements.