Loans - Schedule of Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Loans [Line Items]
Total loans, net of unearned income	$ 41,446,032	$ 39,196,485	$ 38,167,613
Total loans, net of unearned income, percentage	100.00%	100.00%	100.00%
Commercial
Loans [Line Items]
Total loans, net of unearned income	$ 12,725,473	$ 12,549,164	$ 12,259,250
Total loans, net of unearned income, percentage	31.00%	32.00%	32.00%
Commercial real estate
Loans [Line Items]
Total loans, net of unearned income	$ 10,946,180	$ 9,950,947	$ 9,578,184
Total loans, net of unearned income, percentage	26.00%	25.00%	25.00%
Home equity
Loans [Line Items]
Total loans, net of unearned income	$ 343,258	$ 332,698	$ 328,822
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	$ 2,707,603	$ 2,372,383	$ 2,235,459
Total loans, net of unearned income, percentage	7.00%	6.00%	6.00%
Premium finance receivables | Property and casualty insurance
Loans [Line Items]
Total loans, net of unearned income	$ 6,722,747	$ 5,849,459	$ 5,713,340
Total loans, net of unearned income, percentage	16.00%	15.00%	15.00%
Premium finance receivables | Life insurance
Loans [Line Items]
Total loans, net of unearned income	$ 7,931,808	$ 8,090,998	$ 8,004,856
Total loans, net of unearned income, percentage	19.00%	21.00%	21.00%
Consumer and other
Loans [Line Items]
Total loans, net of unearned income	$ 68,963	$ 50,836	$ 47,702
Total loans, net of unearned income, percentage	0.00%	0.00%	0.00%