Securities - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Securities [Abstract]
Gross realized gains from sales of available for sale securities (less than for the three months ended June 30, 2021)	$ 100,000	$ 200,000	$ 1,200,000	$ 300,000
Gross realized losses from sales of available for sale securities			0	0
Other-than-temporary impairment was recorded			$ 0	$ 0