Summary of Significant Accounting Policies - Additional Information (Detail) contract in Millions, Borrowers in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) contract	Dec. 31, 2020 USD ($) Borrowers
Servicing assets, fair value	$ 248,000				$ 275,000				$ 248,000	$ 275,000
Investments	74,892,000				55,093,000				74,892,000	55,093,000
Income tax benefits recognized	1,267,000	$ 1,114,000	$ 1,645,000	$ 1,068,000	777,000	$ 326,000	$ 642,000	$ 192,000	5,094,000	1,937,000
Goodwill, impairment loss									$ 0
Income tax realized on settlement, percentage									50.00%
Interest Income									$ 609,000	269,000
Loan Commitments	10,000,000.0				4,100,000				10,000,000.0	4,100,000
Deposits									4,418,000	6,341,000
Interest expense	1,576,000	$ 1,698,000	$ 1,593,000	$ 1,696,000	1,985,000	$ 2,000,000	$ 1,996,000	$ 2,121,000	$ 6,563,000	8,102,000
Rental payments										$ 259,000
Residential Loan Porfolios [Member]
Number of loan porfolios purchased									42.7	49.1
Core Deposits [Member]
Core deposit intangible asset value	163,000								$ 163,000
Core deposit intangible asset useful life									4 years
Core deposit intangible asset, amortization									$ 41,000
Deposits									36,400,000	$ 42,700,000
Interest expense									273,000	380,000
Low Income Housing Tax Credit [Member]
Investments in low income housing tax credits, commitments	13,600,000				13,600,000				13,600,000	13,600,000
Investment commitments capital call										1,400,000
New investments acquired									614,000
Investments	7,400,000				8,600,000				7,400,000	8,600,000
Investments, commitments remaining for future capital call	$ 1,700,000				$ 2,300,000				1,700,000	2,300,000
Income tax benefits recognized									207,000	263,000
Low income housing tax credits and other benefits recognized									1,400,000	822,000
Amortization expense of investment in low income housing tax credit									$ 1,200,000	$ 1,200,000
Minimum [Member]
Related party interest rate in the entity									10.00%
Furniture and Fixtures [Member] | Minimum [Member]
Estimated useful life									3 years
Furniture and Fixtures [Member] | Maximum [Member]
Estimated useful life									5 years
Leasehold Improvements [Member] | Minimum [Member]
Estimated useful life									7 years
Leasehold Improvements [Member] | Maximum [Member]
Estimated useful life									14 years