Derivatives - Summary Information Regarding Derivatives (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Third party interest rate swaps
Derivative [Line Items]
Derivatives, asset notional amount	$ 85,796,000	$ 153,909,000
Derivatives liability, notional amount	$ 473,273,000	$ 164,427,000
Derivatives, asset average maturity (years)	9 years	8 years 3 months 18 days
Derivative, liability average maturity (years)	9 years 10 months 24 days	12 years
Weighted average rate fixed, other assets	3.51%	4.10%
Weighted average rate fixed, other liabilities	4.32%	5.04%
Derivatives asset, asset fair value	$ 947,000	$ 5,329,000
Derivative liability, liability fair value	$ (25,905,000)	$ (5,707,000)
Derivative asset, average basis spread on variable rate	1.95%	2.13%
Derivative liability, average basis spread on variable rate	1.93%	2.05%
Customer interest rate swaps
Derivative [Line Items]
Derivatives, asset notional amount	$ 473,273,000	$ 164,427,000
Derivatives liability, notional amount	$ 85,796,000	$ 153,909,000
Derivatives, asset average maturity (years)	9 years 10 months 24 days	12 years
Derivative, liability average maturity (years)	9 years	8 years 3 months 18 days
Weighted average rate fixed, other assets	4.32%	5.04%
Weighted average rate fixed, other liabilities	3.51%	4.10%
Derivatives asset, asset fair value	$ 25,905,000	$ 5,707,000
Derivative liability, liability fair value	$ (947,000)	$ (5,329,000)
Derivative asset, average basis spread on variable rate	1.93%	2.05%
Derivative liability, average basis spread on variable rate	1.95%	2.13%
Interest rate swap (cash flow hedge)
Derivative [Line Items]
Derivatives, asset notional amount	$ 30,000,000	$ 30,000,000
Derivatives, asset average maturity (years)	1 year 6 months	2 years 6 months
Weighted average rate fixed, other assets	1.10%	1.10%
Derivatives asset, asset fair value	$ 271,000	$ 1,099,000