Loans Composition (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 30,193,187	$ 28,799,569
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans	10,099,068	9,759,454
Commercial real estate — owner occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans	1,054,969	991,722
Commercial and business lending
Loans and Leases Receivable Disclosure [Line Items]
Loans	11,154,037	10,751,176
Commercial real estate — investor
Loans and Leases Receivable Disclosure [Line Items]
Loans	5,218,980	5,080,344
Real estate construction
Loans and Leases Receivable Disclosure [Line Items]
Loans	2,130,719	2,155,222
Commercial real estate lending
Loans and Leases Receivable Disclosure [Line Items]
Loans	7,349,699	7,235,565
Total commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans	18,503,736	17,986,742
Residential mortgage
Loans and Leases Receivable Disclosure [Line Items]
Loans	8,782,645	8,511,550
Auto finance
Loans and Leases Receivable Disclosure [Line Items]
Loans	2,007,164	1,382,073
Home equity
Loans and Leases Receivable Disclosure [Line Items]
Loans	623,650	624,353
Other consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans	275,993	294,851
Total consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 11,689,451	$ 10,812,828