Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes (Textual) [Abstract]
Federal corporate tax rate	21.00%	21.00%	35.00%
Deferred tax expense for change in tax law			$ 7,416,000
Accelerated amortization expense due to change in tax law			$ 226,000
Carrying value of low income housing tax credit funds	$ 28,480,000	$ 23,885,000
Low income housing tax credit fund commitments	13,137,000
Tax credits	576,000	$ 623,000
Federal
Income Taxes (Textual) [Abstract]
Net operating loss carryforwards	0
Tax credits	63,000
California
Income Taxes (Textual) [Abstract]
Net operating loss carryforwards	18,590,000
Tax credits	$ 648,000