Loans and Leases - Commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans and leases
Loan and lease commitments	$ 5,401,763	$ 5,121,811
Real estate
Loans and leases
Loan and lease commitments	1,509,914	1,476,518
Commercial and Industrial
Loans and leases
Loan and lease commitments	2,406,261	2,185,810
Commercial Real Estate | Real estate
Loans and leases
Loan and lease commitments	78,266	88,331
Construction | Real estate
Loans and leases
Loan and lease commitments	450,856	434,406
Residential | Real estate
Loans and leases
Loan and lease commitments	980,792	953,781
Consumer
Loans and leases
Loan and lease commitments	$ 1,485,588	1,459,467
Lease Financing
Loans and leases
Loan and lease commitments		$ 16