Income Taxes - Reconciliation Of Actual To Expected Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Computed “expected” income tax expense													$ 8,914	$ 5,486	$ 5,056
State income taxes, net													1,639	957	720
Tax-exempt interest on investment securities and loans													(256)	(300)	(307)
Amortization of investment in low income housing tax credit partnerships													3,506	2,668	2,691
Low income housing credits													(3,168)	(2,721)	(2,821)
Revaluation of deferred tax assets													0	0	(470)
Other													(1,076)	(656)	(798)
Total	$ 3,308	$ 3,994	$ 2,014	$ 243	$ 1,100	$ 2,028	$ 1,146	$ 1,160	$ 907	$ 1,129	$ 1,167	$ 868	$ 9,559	$ 5,434	$ 4,071