Allowance for Loan and Lease Losses - Credit Risk Profiles (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) factor	Dec. 31, 2015 USD ($)
Credit quality
Percentage of loans sold with no recourse to not be subject to grading	100.00%
Number of risk factors in internal loan rating system | factor	8
Loans and leases	$ 11,187,695	$ 10,722,030
Loss
Credit quality
Loans and leases	0	0
Commercial Lending
Credit quality
Loans and leases	6,081,082	5,788,042
Commercial Lending | Pass
Credit quality
Loans and leases	5,972,950	5,680,104
Commercial Lending | Special mention
Credit quality
Loans and leases	65,025	71,585
Commercial Lending | Substandard
Credit quality
Loans and leases	39,336	32,076
Commercial Lending | Doubtful
Credit quality
Loans and leases	3,771	4,277
Commercial and Industrial
Credit quality
Loans and leases	3,288,503	3,057,455
Commercial and Industrial | Pass
Credit quality
Loans and leases	3,226,306	2,995,180
Commercial and Industrial | Special mention
Credit quality
Loans and leases	39,701	46,097
Commercial and Industrial | Substandard
Credit quality
Loans and leases	18,898	12,220
Commercial and Industrial | Doubtful
Credit quality
Loans and leases	3,598	3,958
Commercial Real Estate
Credit quality
Loans and leases	2,181,732	2,164,448
Commercial Real Estate | Pass
Credit quality
Loans and leases	2,138,445	2,119,933
Commercial Real Estate | Special mention
Credit quality
Loans and leases	24,266	24,695
Commercial Real Estate | Substandard
Credit quality
Loans and leases	19,021	19,682
Commercial Real Estate | Doubtful
Credit quality
Loans and leases		138
Construction
Credit quality
Loans and leases	424,743	367,460
Construction | Pass
Credit quality
Loans and leases	422,277	366,695
Construction | Special mention
Credit quality
Loans and leases	1,049	765
Construction | Substandard
Credit quality
Loans and leases	1,417
Lease Financing
Credit quality
Loans and leases	186,104	198,679
Lease Financing | Pass
Credit quality
Loans and leases	185,922	198,296
Lease Financing | Special mention
Credit quality
Loans and leases	9	28
Lease Financing | Substandard
Credit quality
Loans and leases		174
Lease Financing | Doubtful
Credit quality
Loans and leases	173	181
Residential and consumer
Credit quality
Loans and leases	5,106,613	4,933,988
Residential and consumer | Performing
Credit quality
Loans and leases	5,069,852	4,889,617
Residential and consumer | Nonperforming and delinquent
Credit quality
Loans and leases	36,761	44,371
Residential
Credit quality
Loans and leases	3,654,525	3,532,427
Residential | Performing
Credit quality
Loans and leases	3,636,780	3,507,756
Residential | Nonperforming and delinquent
Credit quality
Loans and leases	17,745	24,671
Consumer
Credit quality
Loans and leases	1,452,088	1,401,561
Consumer loans | Consumer
Credit quality
Loans and leases	241,092	238,898
Consumer loans | Consumer | Performing
Credit quality
Loans and leases	237,534	236,207
Consumer loans | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	3,558	2,691
Consumer - Auto | Consumer
Credit quality
Loans and leases	868,349	807,957
Consumer - Auto | Consumer | Performing
Credit quality
Loans and leases	856,212	794,692
Consumer - Auto | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	12,137	13,265
Credit Cards | Consumer
Credit quality
Loans and leases	342,647	354,706
Credit Cards | Consumer | Performing
Credit quality
Loans and leases	339,326	350,962
Credit Cards | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	$ 3,321	$ 3,744