Investment Securities (Gross Unrealized Losses and Fair Value by Length of Continuous Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Available-for-sale securities:
Fair value, less than 12 months	$ 1,029	$ 32,180
Unrealized losses, less than 12 months	5	2,541
Fair value, more than 12 months	71,358	50,752
Unrealized losses, more than 12 months	13,934	9,878
Fair Value	72,387	82,932
Unrealized Losses	13,939	12,419
Held-to-maturity securities:
Fair value, less than 12 months		224,974
Unrealized losses, less than 12 months		12,625
Fair value, more than 12 months		268,951
Unrealized losses, more than 12 months		52,238
Fair Value		493,925
Unrealized Losses		64,863
U.S. Government agencies
Available-for-sale securities:
Fair value, less than 12 months	596	1,165
Unrealized losses, less than 12 months	1	4
Fair value, more than 12 months	16,352	16,585
Unrealized losses, more than 12 months	3,994	3,621
Fair Value	16,948	17,750
Unrealized Losses	3,995	3,625
Held-to-maturity securities:
Fair value, less than 12 months		67,332
Unrealized losses, less than 12 months		2,786
Fair value, more than 12 months		67,163
Unrealized losses, more than 12 months		10,815
Fair Value		134,495
Unrealized Losses		13,601
Mortgage-backed-residential
Available-for-sale securities:
Fair value, less than 12 months	433	29,125
Unrealized losses, less than 12 months	4	2,409
Fair value, more than 12 months	53,140	34,167
Unrealized losses, more than 12 months	9,794	6,257
Fair Value	53,573	63,292
Unrealized Losses	9,798	8,666
Held-to-maturity securities:
Fair value, less than 12 months		148,771
Unrealized losses, less than 12 months		9,402
Fair value, more than 12 months		199,649
Unrealized losses, more than 12 months		41,062
Fair Value		348,420
Unrealized Losses		50,464
Other debt securities
Available-for-sale securities:
Fair value, less than 12 months	0	1,890
Unrealized losses, less than 12 months	0	128
Fair value, more than 12 months	1,866	0
Unrealized losses, more than 12 months	146	0
Fair Value	1,866	1,890
Unrealized Losses	$ 146	128
Held-to-maturity securities:
Fair value, less than 12 months		8,091
Unrealized losses, less than 12 months		409
Fair value, more than 12 months		2,139
Unrealized losses, more than 12 months		361
Fair Value		10,230
Unrealized Losses		770
States and political subdivisions
Held-to-maturity securities:
Fair value, less than 12 months		780
Unrealized losses, less than 12 months		28
Fair value, more than 12 months		0
Unrealized losses, more than 12 months		0
Fair Value		780
Unrealized Losses		$ 28