Securities - Securities with Unrealized Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	$ 18,497	$ 13,604
Less than 12 Months, Unrealized Loss	(256)	(176)
12 Months or More, Fair Value	1,452,208	1,494,312
12 Months or More, Unrealized Loss	(299,724)	(275,589)
Total Fair Value	1,470,705	1,507,916
Total Unrealized Loss	(299,980)	(275,765)
Obligations of State and Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	18,497	13,469
Less than 12 Months, Unrealized Loss	(256)	(175)
12 Months or More, Fair Value	653,099	668,223
12 Months or More, Unrealized Loss	(137,716)	(122,199)
Total Fair Value	671,596	681,692
Total Unrealized Loss	(137,972)	(122,374)
MBS/CMO
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	0	135
Less than 12 Months, Unrealized Loss	0	(1)
12 Months or More, Fair Value	621,301	643,172
12 Months or More, Unrealized Loss	(123,251)	(116,012)
Total Fair Value	621,301	643,307
Total Unrealized Loss	(123,251)	(116,013)
US Gov’t Sponsored Entities & Agencies
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Unrealized Loss	0	0
12 Months or More, Fair Value	177,808	182,917
12 Months or More, Unrealized Loss	(38,757)	(37,378)
Total Fair Value	177,808	182,917
Total Unrealized Loss	$ (38,757)	$ (37,378)