Derivatives - Summary Information Regarding Derivatives (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Third party interest rate swaps
Classified in Other Assets:
Notional  Amount	$ 73,075	$ 85,796
Average Maturity (Years)	9 years 6 months	9 years
Weighted  Average Rate Fixed	3.20%	3.51%
Weighted Average Variable Rate	255.00%	195.00%
Fair Value	$ 503	$ 947
Classified in Other Liabilities:
Notional  Amount	$ 907,069	$ 473,273
Average Maturity (Years)	8 years 8 months 12 days	9 years 10 months 24 days
Weighted  Average Rate Fixed	3.79%	4.32%
Weighted Average Variable Rate	199.00%	193.00%
Fair Value	$ (80,231)	$ (25,905)
Customer interest rate swaps
Classified in Other Assets:
Notional  Amount	$ 907,069	$ 473,273
Average Maturity (Years)	8 years 8 months 12 days	9 years 10 months 24 days
Weighted  Average Rate Fixed	3.79%	4.32%
Weighted Average Variable Rate	199.00%	193.00%
Fair Value	$ 80,231	$ 25,905
Classified in Other Liabilities:
Notional  Amount	$ 73,075	$ 85,796
Average Maturity (Years)	9 years 6 months	9 years
Weighted  Average Rate Fixed	3.20%	3.51%
Weighted Average Variable Rate	255.00%	195.00%
Fair Value	$ (503)	$ (947)
Interest rate swap (cash flow hedge)
Classified in Other Assets:
Notional  Amount		$ 30,000
Average Maturity (Years)		1 year 6 months
Weighted  Average Rate Fixed		1.10%
Fair Value		$ 271
Classified in Other Liabilities:
Notional  Amount	$ 30,000
Average Maturity (Years)	6 months
Weighted  Average Rate Fixed	1.10%
Fair Value	$ (143)