Investment Securities Schedule of Amortized Cost and Fair Values of Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Amortized Cost	$ 2,916,610
Gross Unrealized Gains	256
Gross Unrealized Losses	(344,145)
Estimated Fair Value	2,572,721	$ 2,646,767
Amortized Cost, Held to Maturity	1,294,613	1,321,256
Gross Unrealized Gains, Held to Maturity	0	0
Gross Unrealized Losses, Held to Maturity	(207,921)	(196,207)
Debt Securities, Held-to-Maturity, Fair Value	1,086,692	1,125,049
US Government Debt Securities
Schedule of Investments [Line Items]
Amortized Cost	225,542	226,140
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4,904)	(7,655)
Estimated Fair Value	220,638	218,485
US Government Agencies Debt Securities
Schedule of Investments [Line Items]
Amortized Cost	1,044	1,050
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(45)	(42)
Estimated Fair Value	999	1,008
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,206,102	1,284,245
Gross Unrealized Gains	252	283
Gross Unrealized Losses	(152,446)	(178,816)
Estimated Fair Value	1,053,908	1,105,712
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	474,953	459,792
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(50,574)	(37,483)
Estimated Fair Value	424,379	422,309
Collateralized Mortgage Obligations [Member]
Schedule of Investments [Line Items]
Amortized Cost	134,234	147,155
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(13,776)	(13,122)
Estimated Fair Value	120,458	134,033
Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	233,807	242,527
Gross Unrealized Gains	4	18
Gross Unrealized Losses	(28,923)	(29,847)
Estimated Fair Value	204,888	212,698
Amortized Cost, Held to Maturity	431,704	457,325
Gross Unrealized Gains, Held to Maturity	0	0
Gross Unrealized Losses, Held to Maturity	(56,114)	(57,480)
Debt Securities, Held-to-Maturity, Fair Value	375,590	399,845
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	640,928	631,604
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(93,477)	(79,082)
Estimated Fair Value	547,451	552,522
Amortized Cost, Held to Maturity	862,909	863,931
Gross Unrealized Gains, Held to Maturity	0	0
Gross Unrealized Losses, Held to Maturity	(151,807)	(138,727)
Debt Securities, Held-to-Maturity, Fair Value	$ 711,102	725,204
Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost		2,992,513
Gross Unrealized Gains		301
Gross Unrealized Losses		(346,047)
Estimated Fair Value		$ 2,646,767