Loans and Allowance for Loan Losses - Summary of Post-modification Balance of TDRs listed by Type of Modification (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Troubled Debt Restructuring [Line Items]
Post modification balance of TDRs	$ 295	$ 687
Extended maturity and interest only/principal deferred
Financing Receivable, Troubled Debt Restructuring [Line Items]
Post modification balance of TDRs	0	46
Court-ordered concession
Financing Receivable, Troubled Debt Restructuring [Line Items]
Post modification balance of TDRs	295	0
Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Post modification balance of TDRs	$ 0	$ 641