Loans Held for Sale - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Receivables Held For Sale [Abstract]
Net gains from changes in estimated fair value of mortgage loans held for sale	$ 2,354,000	$ 4,000
Total unpaid principal balance of loans held for sale	185,962,000		$ 141,627,000
Loans held for sale, past due	0		0
Loans held for sale, on nonaccrual	$ 0		$ 0