Commitments and Contingencies - Small Business Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Carry amount included in other assets	$ 571,976	$ 573,992
Permanent and short-term construction loans and letter of credit commitments	160,723	205,659
Funded portion of permanent and short-term loans and letters of credit	227,180	211,921
Future funding commitment amount	263,100	293,300
Letters of credit
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	176,324	200,269
Contractual amount net of risk participations	18,400	22,800
Commitments to fund commercial and industrial loans
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	9,748,389	10,313,880
Commitments to fund commercial real estate, construction, and land development loans
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	2,189,478	2,496,656
Commitments under home equity lines of credit
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	2,128,208	2,135,120
Unused credit card lines
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	456,177	453,303
Other loan commitments
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	636,373	654,396
Total letters of credit and unfunded lending commitments
Loss Contingencies [Line Items]
Total letters of credit and unfunded lending commitments	15,334,949	16,253,624
Permanent and short-term construction loans and letter of credit commitments
Loss Contingencies [Line Items]
Contractual amount net of risk participations	7,100	9,700
Funded portion of permanent and short-term loans and letters of credit
Loss Contingencies [Line Items]
Contractual amount net of risk participations	$ 6,600	$ 4,000