Loans and Leases - Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans and leases
Loan and lease commitments	$ 5,679,106	$ 5,401,763
Real estate
Loans and leases
Loan and lease commitments	1,565,196	1,509,914
Commercial and Industrial
Loans and leases
Loan and lease commitments	2,609,587	2,406,261
Commercial Real Estate | Real estate
Loans and leases
Loan and lease commitments	108,911	78,266
Construction | Real estate
Loans and leases
Loan and lease commitments	511,666	450,856
Residential | Real estate
Loans and leases
Loan and lease commitments	944,619	980,792
Consumer
Loans and leases
Loan and lease commitments	$ 1,504,323	$ 1,485,588