Non-interest Income and Expense - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights	$ (779)	$ 106	$ 1,892