Restrictions on Cash and Due from Banks and Interest-earning Deposit Accounts - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Reserve requirement at Federal Reserve Bank	$ 0	$ 11,100
Average balances at Federal Reserve Bank	270,700	138,400
Pledging requirement for credit derivatives and SWAP agreements - cash	$ 100	$ 0