Commitments and Contingencies - Small Business Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Carrying amount included in other assets	$ 573,992	$ 488,944
Amount of future funding commitments	293,266	283,212
Permanent and short-term construction loans and letter of credit commitments	205,659	177,998
Funded portion of permanent and short-term loans and letters of credit	211,921	234,166
Letters of credit
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	200,269	220,622
Contractual amount net of risk participations	22,800	25,700
Commitments to fund commercial and industrial loans
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	10,313,880	9,970,733
Commitments to fund commercial real estate, construction, and land development loans
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	2,496,656	3,629,531
Commitments under home equity lines of credit
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	2,135,120	2,156,641
Unused credit card lines
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	453,303	461,443
Other loan commitments
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	654,396	742,976
Guarantee Obligations
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	16,253,624	17,181,946
Permanent and Short-term Construction Loans and Letter of Credit Commitments
Loss Contingencies [Line Items]
Contractual amount net of risk participations	9,700	4,700
Funded Portion of Permanent and Short-term Loans and Letters of Credit
Loss Contingencies [Line Items]
Contractual amount net of risk participations	$ 4,000	$ 6,900