Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accounting Policies [Abstract]
Interest bearing amounts held at other financial institutions	$ 28.7	$ 23.6	$ 28.7	$ 23.6
Dilutive effect of common stock issuable upon exercise of options	86,528	261,960	150,946	273,663
Anti-dilutive shares	540,525	118,029	371,885	118,029