Loans and Leases and the Allowance for Credit Losses - Schedule of Loan and Lease Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loan and lease portfolio
Loans and Leases	$ 11,793,608	$ 10,990,892
Commercial
Loan and lease portfolio
Loans and Leases	5,016,867	4,213,827
Commercial | Commercial and Industrial
Loan and lease portfolio
Loans and Leases	1,908,482	1,379,152
Commercial | Commercial Mortgage
Loan and lease portfolio
Loans and Leases	2,745,611	2,518,051
Commercial | Construction
Loan and lease portfolio
Loans and Leases	250,943	194,170
Commercial | Lease Financing
Loan and lease portfolio
Loans and Leases	111,831	122,454
Consumer
Loan and lease portfolio
Loans and Leases	6,776,741	6,777,065
Consumer | Other
Loan and lease portfolio
Loans and Leases	417,090	489,606
Consumer | Residential Mortgage
Loan and lease portfolio
Loans and Leases	4,044,228	3,891,100
Consumer | Home Equity
Loan and lease portfolio
Loans and Leases	1,605,486	1,676,073
Consumer | Automobile
Loan and lease portfolio
Loans and Leases	$ 709,937	$ 720,286