Loan Portfolio and Allowance for Credit Losses, Based on Impairment Review Method (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	$ 0		$ 0
Collectively evaluated for impairment	47,226		46,032
Total ending allowance balance	47,226	$ 46,914	46,032	$ 45,517	$ 45,285
Loans [Abstract]
Individually evaluated for impairment	25,589		25,695
Collectively evaluated for impairment	4,934,692		4,707,506
Total loans	4,960,281		4,733,201
Commercial Loans [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	2,713		2,596
Total ending allowance balance	2,713	2,610	2,596	2,429	2,274
Loans [Abstract]
Individually evaluated for impairment	962		646
Collectively evaluated for impairment	267,680		230,365
Total loans	268,642		231,011
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	44,285		43,271
Total ending allowance balance	44,285	44,067	43,271	42,944	42,880
Loans [Abstract]
Individually evaluated for impairment	24,521		24,967
Collectively evaluated for impairment	4,650,513		4,464,916
Total loans	4,675,034		4,489,883
Installment Loans [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	228		165
Total ending allowance balance	228	$ 237	165	$ 144	$ 131
Loans [Abstract]
Individually evaluated for impairment	106		82
Collectively evaluated for impairment	16,499		12,225
Total loans	$ 16,605		$ 12,307