Loans and Leases and the Allowance for Credit Losses - Schedule of Loan and Lease Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Loan and lease portfolio
Loans and Leases	$ 11,940,020	$ 10,990,892
Commercial
Loan and lease portfolio
Loans and Leases	5,100,686	4,213,827
Commercial | Commercial and Industrial
Loan and lease portfolio
Loans and Leases	1,875,293	1,379,152
Commercial | Commercial Mortgage
Loan and lease portfolio
Loans and Leases	2,854,829	2,518,051
Commercial | Construction
Loan and lease portfolio
Loans and Leases	259,798	194,170
Commercial | Lease Financing
Loan and lease portfolio
Loans and Leases	110,766	122,454
Consumer
Loan and lease portfolio
Loans and Leases	6,839,334	6,777,065
Consumer | Other
Loan and lease portfolio
Loans and Leases	395,483	489,606
Consumer | Residential Mortgage
Loan and lease portfolio
Loans and Leases	4,130,513	3,891,100
Consumer | Home Equity
Loan and lease portfolio
Loans and Leases	1,604,538	1,676,073
Consumer | Automobile
Loan and lease portfolio
Loans and Leases	$ 708,800	$ 720,286