Loans and Leases - Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans and leases
Loan and lease commitments	$ 5,438,176	$ 5,121,811
Real estate
Loans and leases
Loan and lease commitments	1,537,681	1,476,518
Commercial and Industrial
Loans and leases
Loan and lease commitments	2,406,088	2,185,810
Commercial Real Estate | Real estate
Loans and leases
Loan and lease commitments	80,719	88,331
Construction | Real estate
Loans and leases
Loan and lease commitments	470,247	434,406
Residential | Real estate
Loans and leases
Loan and lease commitments	986,715	953,781
Consumer
Loans and leases
Loan and lease commitments	$ 1,494,407	1,459,467
Lease Financing
Loans and leases
Loan and lease commitments		$ 16