Loan Portfolio and Allowance for Credit Losses, Based on Impairment Review Method (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	$ 0	$ 0
Collectively evaluated for impairment	46,178	44,267
Total ending allowance balance	46,178
Total ending allowance balance		44,267	$ 49,991	$ 49,595
Loans [Abstract]
Individually evaluated for impairment	17,922	18,504
Collectively evaluated for impairment	4,446,432	4,420,275
Total loans	4,464,354
Total loans		4,438,779
Commercial [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	2,177	3,135
Total ending allowance balance	2,177
Total ending allowance balance		3,135	4,052	4,140
Loans [Abstract]
Individually evaluated for impairment	305	232
Collectively evaluated for impairment	192,103	199,968
Total loans	192,408
Total loans		200,200
1 to 4 Family Residential Real Estate [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	43,931	40,689
Total ending allowance balance	43,931
Total ending allowance balance		40,689	45,507	44,950
Loans [Abstract]
Individually evaluated for impairment	17,617	18,272
Collectively evaluated for impairment	4,244,934	4,210,891
Total loans	4,262,551
Total loans		4,229,163
Installment [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	70	443
Total ending allowance balance	70
Total ending allowance balance		443	$ 432	$ 505
Loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	9,395	9,416
Total loans	$ 9,395
Total loans		$ 9,416