Loans and Leases - Commitments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans and leases
Loan and lease commitments	$ 5,563,389	$ 5,401,763
Real estate
Loans and leases
Loan and lease commitments	1,608,186	1,509,914
Commercial and Industrial
Loans and leases
Loan and lease commitments	2,449,440	2,406,261
Commercial Real Estate | Real estate
Loans and leases
Loan and lease commitments	91,565	78,266
Construction | Real estate
Loans and leases
Loan and lease commitments	530,143	450,856
Residential | Real estate
Loans and leases
Loan and lease commitments	986,478	980,792
Consumer
Loans and leases
Loan and lease commitments	$ 1,505,763	$ 1,485,588