Borrowings - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Pledged loans receivable, carrying value	$ 1,350,000,000
Total borrowing capacity available from the collateral	1,110,000,000
Available borrowing capacity	878,400,000
Available for use through the Federal Reserve Bank of San Francisco Discount Window	29,600,000
Pledged loans, carrying values	30,200,000
Borrowings	0
Advances from the FHLB	90,000,000	$ 55,000,000
Increase in the advances from the FHLB	35,000,000.0
Interest on subordinated debentures	$ 763,000	$ 3,379,000	$ 1,077,000
Weighted-average interest rates	1.89%	1.94%	0.90%
Overnight advances from federal home loan banks	$ 15,000,000.0