Securities - Schedule of Securities Available-for-Sale (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,961,667,000	$ 2,094,826,000
Gross Unrealized Gains	1,202,000	695,000
Gross Unrealized Losses	(292,613,000)	(333,852,000)
Allowance for Credit Losses	0	0
Fair Value	1,670,256,000	1,761,669,000
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,984,000	64,097,000
Gross Unrealized Gains	1,000	22,000
Gross Unrealized Losses	0	0
Allowance for Credit Losses	0	0
Fair Value	1,985,000	64,119,000
Obligations of State and Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	917,686,000	939,193,000
Gross Unrealized Gains	1,201,000	673,000
Gross Unrealized Losses	(138,247,000)	(162,014,000)
Allowance for Credit Losses	0	0
Fair Value	780,640,000	777,852,000
MBS/CMO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	811,898,000	846,519,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(119,542,000)	(131,838,000)
Allowance for Credit Losses	0	0
Fair Value	692,356,000	714,681,000
US Gov’t Sponsored Entities & Agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	230,099,000	245,017,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(34,824,000)	(40,000,000)
Allowance for Credit Losses	0	0
Fair Value	$ 195,275,000	$ 205,017,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
-Name Accounting Standards Codification
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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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