Loans and Leases and the Allowance for Credit Losses - Schedule of Loan and Lease Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loan and lease portfolio
Loans and Leases	$ 12,072,750	$ 11,940,020
Commercial
Loan and lease portfolio
Loans and Leases	4,992,024	5,100,686
Commercial | Commercial and Industrial
Loan and lease portfolio
Loans and Leases	1,325,446	1,357,610
Commercial | PPP
Loan and lease portfolio
Loans and Leases	268,480	517,683
Commercial | Commercial Mortgage
Loan and lease portfolio
Loans and Leases	2,994,520	2,854,829
Commercial | Construction
Loan and lease portfolio
Loans and Leases	296,052	259,798
Commercial | Lease Financing
Loan and lease portfolio
Loans and Leases	107,526	110,766
Consumer
Loan and lease portfolio
Loans and Leases	7,080,726	6,839,334
Consumer | Other
Loan and lease portfolio
Loans and Leases	400,723	395,483
Consumer | Residential Mortgage
Loan and lease portfolio
Loans and Leases	4,272,540	4,130,513
Consumer | Home Equity
Loan and lease portfolio
Loans and Leases	1,680,229	1,604,538
Consumer | Automobile
Loan and lease portfolio
Loans and Leases	$ 727,234	$ 708,800