Investment Securities - Available for Sale and Held for Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Available-for-sale: [Abstract]
Amortized Cost	$ 1,377,803	$ 1,432,372
Gross Unrealized Gains	62	143
Gross Unrealized (Losses)	(213,532)	(213,530)
Fair Value	1,164,333	1,218,985
Held-to-maturity: [Abstract]
Held-to-maturity	2,971	2,954
Gross Unrealized Gains	0	0
Unrealized (Losses)	0	0
Fair Value	2,971	2,954
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale: [Abstract]
Amortized Cost	246,712	252,934
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	(31,558)	(32,407)
Fair Value	215,154	220,527
Obligations of States and Political Subdivisions
Available-for-sale: [Abstract]
Amortized Cost	338,377	347,409
Gross Unrealized Gains	61	134
Gross Unrealized (Losses)	(56,422)	(59,845)
Fair Value	282,016	287,698
Mortgage-backed Securities: GSE Residential
Available-for-sale: [Abstract]
Amortized Cost	713,394	744,636
Gross Unrealized Gains	1	3
Gross Unrealized (Losses)	(119,647)	(116,759)
Fair Value	593,748	627,880
Other Securities
Available-for-sale: [Abstract]
Amortized Cost	79,320	87,393
Gross Unrealized Gains	0	6
Gross Unrealized (Losses)	(5,905)	(4,519)
Fair Value	73,415	82,880
Other Investments
Held-to-maturity: [Abstract]
Held-to-maturity	2,971	2,954
Gross Unrealized Gains	0	0
Unrealized (Losses)	0	0
Fair Value	$ 2,971	$ 2,954