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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Loans and Allowance for Credit Losses - Schedule of Composition of Loans and Impact of Adoption (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	$ 33,623,319		$ 32,991,927
Allowance for credit losses on loans	(319,713)	$ (298,711)	(307,610)	$ (303,671)
Net loans	33,303,606		32,684,317
Taxable	487,361	410,375
Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	0		0
Net loans	0		0
Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	33,623,319		32,991,927
Allowance for credit losses on loans	(319,713)		(307,610)
Net loans	33,303,606		32,684,317
Taxable	88,900		93,700
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	9,648,269		9,512,230
Allowance for credit losses on loans	(123,437)	(125,768)	(118,333)	(120,612)
Commercial \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	(232,045)		(232,764)
Commercial \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	9,416,224		9,279,466
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	14,653,958		14,140,629
Allowance for credit losses on loans	(160,640)	(135,348)	(155,099)	(138,244)
Commercial real estate \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	(172,659)		(169,058)
Commercial real estate \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	14,481,299		13,971,571
BBCC
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses on loans	(3,163)	(2,316)	(2,887)	(2,431)
BBCC \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	404,704		401,822
BBCC \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	404,704		401,822
Residential real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	6,661,379		6,699,443
Allowance for credit losses on loans	(21,899)	(20,207)	(20,837)	(21,916)
Residential real estate \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	0		0
Residential real estate \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	6,661,379		6,699,443
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	2,659,713		2,639,625
Consumer \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	(2,659,713)		(2,639,625)
Indirect
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	1,091,998		1,050,982
Allowance for credit losses on loans	(1,218)	(1,434)	(1,236)	(1,532)
Indirect \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	1,091,998		1,050,982
Indirect \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	1,091,998		1,050,982
Direct
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	506,305		523,172
Allowance for credit losses on loans	(2,952)	(6,766)	(3,169)	(12,116)
Direct \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	506,305		523,172
Direct \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	506,305		523,172
Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	1,061,410		1,065,471
Allowance for credit losses on loans	(6,404)	$ (6,872)	(6,049)	$ (6,820)
Home equity \| Portfolio Segment Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	1,061,410		1,065,471
Home equity \| Portfolio Segment After Reclassifications
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	1,061,410		1,065,471
Direct Finance Leases
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, net of unearned income	$ 161,700		$ 169,700