Allowance for Credit Losses - Schedule of Aging of the Company's Loan Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Nonaccrual	$ 118,743	$ 98,379
Loans, net of unearned income	42,131,831	39,196,485
Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	31,279
Loans, net of unearned income	150,583	164,788
Commercial
Financing Receivable, Past Due [Line Items]
Nonaccrual	38,940	35,579
Loans, net of unearned income	12,832,053	12,549,164
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	11,344,164	9,950,947
Commercial real estate | Construction and development
Financing Receivable, Past Due [Line Items]
Nonaccrual	2,205	416
Loans, net of unearned income	2,084,041	1,486,930
Commercial real estate | Non-construction
Financing Receivable, Past Due [Line Items]
Nonaccrual	33,254	5,971
Loans, net of unearned income	9,260,123	8,464,017
Home equity
Financing Receivable, Past Due [Line Items]
Nonaccrual	1,341	1,487
Loans, net of unearned income	343,976	332,698
Residential real estate loans, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,769,666	2,372,383
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	15,391	10,171
Loans, net of unearned income	2,619,083	2,207,595
Premium finance receivables | Property & casualty insurance loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	27,590	13,470
Loans, net of unearned income	6,903,529	5,849,459
Premium finance receivables | Life insurance loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	0
Loans, net of unearned income	7,877,943	8,090,998
Consumer and other
Financing Receivable, Past Due [Line Items]
Nonaccrual	22	6
Loans, net of unearned income	60,500	50,836
Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	118,743	67,100
Loans, net of unearned income	41,981,248	39,031,697
90+ days and still accruing
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	77,975	81,047
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	57,688	47,450
90+ days and still accruing | Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	98	462
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 insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	20,135	15,841
90+ days and still accruing | Premium finance receivables | Life insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	17,245
90+ days and still accruing | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	54	49
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	20,287	33,597
60-89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	70,107	48,924
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	250	984
60-89 days past due | Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	19,488	21,128
60-89 days past due | Commercial real estate | Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	251	361
60-89 days past due | Commercial real estate | Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	8,264	1,883
60-89 days past due | Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	62	0
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	2,325	4,364
60-89 days past due | Premium finance receivables | Property & casualty insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	23,236	14,926
60-89 days past due | Premium finance receivables | Life insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	16,206	5,260
60-89 days past due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	25	18
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	69,857	47,940
30-59 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	227,976	210,595
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	328	1,584
30-59 days past due | Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	85,743	56,696
30-59 days past due | Commercial real estate | Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,343	14,390
30-59 days past due | Commercial real estate | Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	19,291	16,285
30-59 days past due | Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,263	2,152
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	22,942	9,982
30-59 days past due | Premium finance receivables | Property & casualty insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	50,437	40,557
30-59 days past due | Premium finance receivables | Life insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	45,464	68,725
30-59 days past due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	165	224
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	227,648	209,011
Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	41,637,030	38,757,540
Current | Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	92,317	83,491
Current | Commercial
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	12,687,784	12,435,299
Current | Commercial real estate | Construction and development
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,080,242	1,471,763
Current | Commercial real estate | Non-construction
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	9,199,314	8,439,878
Current | Home equity
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	340,310	329,059
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	2,578,425	2,183,078
Current | Premium finance receivables | Property & casualty insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	6,782,131	5,764,665
Current | Premium finance receivables | Life insurance loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	7,816,273	7,999,768
Current | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	60,234	50,539
Current | Total loans, net of unearned income, excluding early buy-out loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 41,544,713	$ 38,674,049