Fair Value Measurement and Fair Value of Financial Instruments - Fair Value of Assets Measured on Non-recurring Basis (Detail) - Fair Value, Measurements, Non-recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets:
Individually evaluated loans	$ 2,297	$ 2,417
Loans held for sale	1,230	1,335
(Level 1)
Assets:
Individually evaluated loans	0	0
Loans held for sale	0	0
(Level 2)
Assets:
Individually evaluated loans	0	0
Loans held for sale	1,230	1,335
(Level 3)
Assets:
Individually evaluated loans	2,297	2,417
Loans held for sale	$ 0	$ 0