Allowance for Loan and Lease Losses - Credit Risk Profiles (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) factor	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Credit quality
Percentage of loans sold with no recourse not subject to grading	100.00%
Number of risk factors in internal loan rating system | factor	8
Loans and leases	$ 11,520,378	$ 10,722,030	$ 10,023,590
Loss
Credit quality
Loans and leases	0	0
Commercial Lending
Credit quality
Loans and leases	6,213,147	5,788,042
Commercial Lending | Pass
Credit quality
Loans and leases	6,089,637	5,680,104
Commercial Lending | Special mention
Credit quality
Loans and leases	69,735	71,585
Commercial Lending | Substandard
Credit quality
Loans and leases	51,856	32,076
Commercial Lending | Doubtful
Credit quality
Loans and leases	1,919	4,277
Commercial and Industrial
Credit quality
Loans and leases	3,239,600	3,057,455	2,697,142
Commercial and Industrial | Pass
Credit quality
Loans and leases	3,166,304	2,995,180
Commercial and Industrial | Special mention
Credit quality
Loans and leases	41,719	46,097
Commercial and Industrial | Substandard
Credit quality
Loans and leases	29,811	12,220
Commercial and Industrial | Doubtful
Credit quality
Loans and leases	1,766	3,958
Commercial Real Estate
Credit quality
Loans and leases	2,343,495	2,164,448	2,047,465
Commercial Real Estate | Pass
Credit quality
Loans and leases	2,298,839	2,119,933
Commercial Real Estate | Special mention
Credit quality
Loans and leases	23,859	24,695
Commercial Real Estate | Substandard
Credit quality
Loans and leases	20,797	19,682
Commercial Real Estate | Doubtful
Credit quality
Loans and leases		138
Construction
Credit quality
Loans and leases	450,012	367,460	470,061
Construction | Pass
Credit quality
Loans and leases	445,149	366,695
Construction | Special mention
Credit quality
Loans and leases	3,789	765
Construction | Substandard
Credit quality
Loans and leases	1,074
Lease Financing
Credit quality
Loans and leases	180,040	198,679	244,298
Lease Financing | Pass
Credit quality
Loans and leases	179,345	198,296
Lease Financing | Special mention
Credit quality
Loans and leases	368	28
Lease Financing | Substandard
Credit quality
Loans and leases	174	174
Lease Financing | Doubtful
Credit quality
Loans and leases	153	181
Residential and consumer
Credit quality
Loans and leases	5,307,231	4,933,988
Residential and consumer | Performing
Credit quality
Loans and leases	5,265,885	4,889,617
Residential and consumer | Nonperforming and delinquent
Credit quality
Loans and leases	41,346	44,371
Residential
Credit quality
Loans and leases	3,796,459	3,532,427	3,338,021
Residential | Performing
Credit quality
Loans and leases	3,778,070	3,507,756
Residential | Nonperforming and delinquent
Credit quality
Loans and leases	18,389	24,671
Consumer
Credit quality
Loans and leases	1,510,772	1,401,561	$ 1,226,603
Consumer loans | Consumer
Credit quality
Loans and leases	243,512	238,898
Consumer loans | Consumer | Performing
Credit quality
Loans and leases	240,185	236,207
Consumer loans | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	3,327	2,691
Consumer - Auto | Consumer
Credit quality
Loans and leases	922,756	807,957
Consumer - Auto | Consumer | Performing
Credit quality
Loans and leases	906,829	794,692
Consumer - Auto | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	15,927	13,265
Credit Cards | Consumer
Credit quality
Loans and leases	344,504	354,706
Credit Cards | Consumer | Performing
Credit quality
Loans and leases	340,801	350,962
Credit Cards | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	$ 3,703	$ 3,744