Interest Rate Swaps - Amounts and Locations of Activity Related to Back-to-Back Interest Rate Swaps (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
3rd Party interest rate swaps
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Notional Amount, Asset	$ 35,382	$ 23,152
Average Maturity (in years)	7 years 8 months 12 days	7 years 2 months 12 days
Weighted Average Fixed Rate	4.13%	3.85%
Assets (Liabilities), at fair value	$ 1,877	$ 485
Customer interest rate swaps
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Notional Amount, Liability	$ (35,382)	$ (23,152)
Average Maturity (in years)	7 years 8 months 12 days	7 years 2 months 12 days
Weighted Average Fixed Rate	4.13%	3.85%
Assets (Liabilities), at fair value	$ (1,877)	$ (485)
LIBOR | 3rd Party interest rate swaps
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative basis spread on variable rate	2.27%	2.24%
LIBOR | Customer interest rate swaps
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative basis spread on variable rate	2.27%	2.24%