Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Unrealized losses resulting in deferred tax asset		$ (9,300,000)
Deferred tax assets from unrealized losses on certain investments in debt securities		2,287,000	$ 0
Unrealized gains resulting in a deferred tax liability			26,300,000
Deferred tax liability from unrealized gains on certain investments in debt securities		0	5,890,000
Net deferred tax assets		27,321,000	23,629,000
Deferred tax assets		27,321,000	23,629,000
Accrual for income tax interest or penalties		0
Income tax benefit related to share-based compensation		900,000	100,000	$ 800,000
Amortization reflected as income expense related to affordable housing project investments		1,600,000	900,000	900,000
Affordable housing project tax credits		1,200,000	800,000	800,000
Affordable housing project tax benefits		700,000	200,000	200,000
Carrying value of affordable housing tax credits		30,100,000	16,400,000
Affordable housing tax credits, unfunded amounts		23,200,000	9,900,000
Unrecognized income tax benefits		0
Tax expense (benefit) from change in enacted tax rate		33,335,000	21,122,000	27,008,000
Income tax credit and deferred tax asset related to adoption of CECL			5,500,000
Income tax benefit from CARES act		0	375,000	$ 0
U.S. Federal
Operating Loss Carryforwards [Line Items]
Net deferred tax assets		20,800,000	18,000,000
Deferred tax assets		2,100,000
State
Operating Loss Carryforwards [Line Items]
Net deferred tax assets		6,500,000	$ 5,600,000
Deferred tax assets		1,200,000
Tax expense (benefit) from change in enacted tax rate	$ 1,100,000	$ (800,000)