Allowance for Loan and Lease Losses - Credit Risk Profiles (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) factor	Dec. 31, 2016 USD ($)
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	$ 11,781,496	$ 11,520,378
Loss
Credit quality
Loans and leases	0	0
Commercial Lending
Credit quality
Loans and leases	6,413,858	6,213,147
Commercial Lending | Pass
Credit quality
Loans and leases	6,258,817	6,089,637
Commercial Lending | Special mention
Credit quality
Loans and leases	112,345	69,735
Commercial Lending | Substandard
Credit quality
Loans and leases	41,123	51,856
Commercial Lending | Doubtful
Credit quality
Loans and leases	1,573	1,919
Commercial and Industrial
Credit quality
Loans and leases	3,243,508	3,239,600
Commercial and Industrial | Pass
Credit quality
Loans and leases	3,135,208	3,166,304
Commercial and Industrial | Special mention
Credit quality
Loans and leases	88,315	41,719
Commercial and Industrial | Substandard
Credit quality
Loans and leases	18,565	29,811
Commercial and Industrial | Doubtful
Credit quality
Loans and leases	1,420	1,766
Commercial Real Estate
Credit quality
Loans and leases	2,532,253	2,343,495
Commercial Real Estate | Pass
Credit quality
Loans and leases	2,492,073	2,298,839
Commercial Real Estate | Special mention
Credit quality
Loans and leases	18,938	23,859
Commercial Real Estate | Substandard
Credit quality
Loans and leases	21,242	20,797
Construction
Credit quality
Loans and leases	469,741	450,012
Construction | Pass
Credit quality
Loans and leases	464,394	445,149
Construction | Special mention
Credit quality
Loans and leases	4,273	3,789
Construction | Substandard
Credit quality
Loans and leases	1,074	1,074
Lease Financing
Credit quality
Loans and leases	168,356	180,040
Lease Financing | Pass
Credit quality
Loans and leases	167,142	179,345
Lease Financing | Special mention
Credit quality
Loans and leases	819	368
Lease Financing | Substandard
Credit quality
Loans and leases	242	174
Lease Financing | Doubtful
Credit quality
Loans and leases	153	153
Residential and consumer
Credit quality
Loans and leases	5,367,638	5,307,231
Residential and consumer | Performing
Credit quality
Loans and leases	5,337,423	5,265,885
Residential and consumer | Nonperforming and delinquent
Credit quality
Loans and leases	30,215	41,346
Residential
Credit quality
Loans and leases	3,864,509	3,796,459
Residential | Performing
Credit quality
Loans and leases	3,852,789	3,778,070
Residential | Nonperforming and delinquent
Credit quality
Loans and leases	11,720	18,389
Consumer
Credit quality
Loans and leases	1,503,129	1,510,772
Consumer loans | Consumer
Credit quality
Loans and leases	238,796	243,512
Consumer loans | Consumer | Performing
Credit quality
Loans and leases	235,539	240,185
Consumer loans | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	3,257	3,327
Consumer - Auto | Consumer
Credit quality
Loans and leases	942,402	922,756
Consumer - Auto | Consumer | Performing
Credit quality
Loans and leases	930,683	906,829
Consumer - Auto | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	11,719	15,927
Credit Cards | Consumer
Credit quality
Loans and leases	321,931	344,504
Credit Cards | Consumer | Performing
Credit quality
Loans and leases	318,412	340,801
Credit Cards | Consumer | Nonperforming and delinquent
Credit quality
Loans and leases	$ 3,519	$ 3,703