Loans - Schedule of Loan Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Loans [Line Items]
Total loans, net of unearned income	$ 55,654,947	$ 53,105,101	$ 51,041,679
Total loans, net of unearned income, percentage	100.00%	100.00%	100.00%
Commercial
Loans [Line Items]
Total loans, net of unearned income	$ 18,281,311	$ 17,044,686	$ 16,387,431
Total loans, net of unearned income, percentage	33.00%	32.00%	32.00%
Commercial real estate
Loans [Line Items]
Total loans, net of unearned income	$ 14,270,607	$ 13,940,736	$ 13,292,010
Total loans, net of unearned income, percentage	26.00%	26.00%	26.00%
Home equity
Loans [Line Items]
Total loans, net of unearned income	$ 491,782	$ 480,525	$ 466,815
Total loans, net of unearned income, percentage	1.00%	1.00%	1.00%
Residential real estate
Loans [Line Items]
Total loans, net of unearned income	$ 4,542,692	$ 4,317,232	$ 3,948,782
Total loans, net of unearned income, percentage	8.00%	8.00%	8.00%
Premium finance receivables—property & casualty \| Premium finance receivables—property & casualty
Loans [Line Items]
Total loans, net of unearned income	$ 8,612,023	$ 8,183,416	$ 8,323,176
Total loans, net of unearned income, percentage	15.00%	16.00%	16.00%
Premium finance receivables—property & casualty \| Premium finance receivables—life insurance
Loans [Line Items]
Total loans, net of unearned income	$ 9,312,521	$ 9,023,642	$ 8,506,960
Total loans, net of unearned income, percentage	17.00%	17.00%	17.00%
Consumer and other
Loans [Line Items]
Total loans, net of unearned income	$ 144,011	$ 114,864	$ 116,505
Total loans, net of unearned income, percentage	0.00%	0.00%	0.00%