Allowance for Credit Losses - Schedule of Aging of the Company's Loan Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Nonaccrual	$ 166,651	$ 154,641
Loans, net of unearned income	53,105,101	48,055,037
Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	0
Loans, net of unearned income	145,793	156,756
Commercial
Financing Receivable, Past Due [Line Items]
Nonaccrual	78,059	73,490
Loans, net of unearned income	17,044,686	15,574,551
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,940,736	12,903,944
Commercial real estate \| Construction and development
Financing Receivable, Past Due [Line Items]
Nonaccrual	2,976	2,282
Loans, net of unearned income	2,409,582	2,434,081
Commercial real estate \| Non-construction
Financing Receivable, Past Due [Line Items]
Nonaccrual	22,171	18,760
Loans, net of unearned income	11,531,154	10,469,863
Home equity
Financing Receivable, Past Due [Line Items]
Nonaccrual	1,221	1,117
Loans, net of unearned income	480,525	445,028
Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,317,232	3,612,765
Residential real estate loans, excluding early buy-out loans \| Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	32,862	23,762
Loans, net of unearned income	4,171,439	3,456,009
Premium finance receivables—property & casualty \| Premium finance receivables—property & casualty
Financing Receivable, Past Due [Line Items]
Nonaccrual	29,354	28,797
Loans, net of unearned income	8,183,416	7,272,042
Premium finance receivables—property & casualty \| Premium finance receivables—life insurance
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	6,431
Loans, net of unearned income	9,023,642	8,147,145
Consumer and other
Financing Receivable, Past Due [Line Items]
Nonaccrual	8	2
Loans, net of unearned income	114,864	99,562
Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	166,651	154,641
Loans, net of unearned income	52,959,308	47,898,281
90+ days and still accruing
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	73,005	50,134
90+ days and still accruing \| Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	53,848	33,952
90+ days and still accruing \| Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	104
90+ days and still accruing \| Commercial real estate \| Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
90+ days and still accruing \| Commercial real estate \| Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
90+ days and still accruing \| Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
90+ days and still accruing \| Residential real estate loans, excluding early buy-out loans \| Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
90+ days and still accruing \| Premium finance receivables—property & casualty \| Premium finance receivables—property & casualty
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	19,115	16,031
90+ days and still accruing \| Premium finance receivables—property & casualty \| Premium finance receivables—life insurance
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
90+ days and still accruing \| Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	42	47
90+ days and still accruing \| Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	19,157	16,182
60-89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	95,006	164,988
60-89 days past due \| Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	204	618
60-89 days past due \| Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	22,952	54,844
60-89 days past due \| Commercial real estate \| Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,260	1,339
60-89 days past due \| Commercial real estate \| Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	18,269	9,182
60-89 days past due \| Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,112	1,233
60-89 days past due \| Residential real estate loans, excluding early buy-out loans \| Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	7,562	5,708
60-89 days past due \| Premium finance receivables—property & casualty \| Premium finance receivables—property & casualty
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	29,294	19,042
60-89 days past due \| Premium finance receivables—property & casualty \| Premium finance receivables—life insurance
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,887	72,963
60-89 days past due \| Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	466	59
60-89 days past due \| Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	94,802	164,370
30-59 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	265,982	252,223
30-59 days past due \| Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,316	2,335
30-59 days past due \| Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	90,205	92,551
30-59 days past due \| Commercial real estate \| Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,456	4,634
30-59 days past due \| Commercial real estate \| Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	52,145	26,132
30-59 days past due \| Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,818	2,148
30-59 days past due \| Residential real estate loans, excluding early buy-out loans \| Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	24,908	18,917
30-59 days past due \| Premium finance receivables—property & casualty \| Premium finance receivables—property & casualty
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	57,685	68,219
30-59 days past due \| Premium finance receivables—property & casualty \| Premium finance receivables—life insurance
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	22,806	36,405
30-59 days past due \| Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	643	882
30-59 days past due \| Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	264,666	249,888
Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	52,504,457	47,433,051
Current \| Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	90,425	119,851
Current \| Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	16,853,470	15,353,562
Current \| Commercial real estate \| Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,391,890	2,425,826
Current \| Commercial real estate \| Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	11,438,569	10,415,789
Current \| Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	475,374	440,530
Current \| Residential real estate loans, excluding early buy-out loans \| Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,106,107	3,407,622
Current \| Premium finance receivables—property & casualty \| Premium finance receivables—property & casualty
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	8,047,968	7,139,953
Current \| Premium finance receivables—property & casualty \| Premium finance receivables—life insurance
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	8,986,949	8,031,346
Current \| Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	113,705	98,572
Current \| Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 52,414,032	$ 47,313,200