Loans and Leases and the Allowance for Credit Losses - Schedule of Loan and Lease Portfolio (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Loan and lease portfolio
Loans and Leases	$ 12,140,703	$ 11,940,020
Commercial
Loan and lease portfolio
Loans and Leases	5,259,371	5,100,686
Commercial | Commercial and Industrial
Loan and lease portfolio
Loans and Leases	2,013,981	1,875,293
Commercial | Commercial Mortgage
Loan and lease portfolio
Loans and Leases	2,859,246	2,854,829
Commercial | Construction
Loan and lease portfolio
Loans and Leases	281,164	259,798
Commercial | Lease Financing
Loan and lease portfolio
Loans and Leases	104,980	110,766
Consumer
Loan and lease portfolio
Loans and Leases	6,881,332	6,839,334
Consumer | Other
Loan and lease portfolio
Loans and Leases	376,449	395,483
Consumer | Residential Mortgage
Loan and lease portfolio
Loans and Leases	4,216,976	4,130,513
Consumer | Home Equity
Loan and lease portfolio
Loans and Leases	1,577,500	1,604,538
Consumer | Automobile
Loan and lease portfolio
Loans and Leases	$ 710,407	$ 708,800