Allowance for Loan and Lease Losses - Credit Risk Profiles (Details) $ in Thousands	6 Months Ended
	Jun. 30, 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	$ 12,062,392	$ 11,520,378
Loss
Credit quality
Loans and leases	0	0
Commercial Lending
Credit quality
Loans and leases	6,613,041	6,213,147
Commercial Lending | Pass
Credit quality
Loans and leases	6,457,899	6,089,637
Commercial Lending | Special mention
Credit quality
Loans and leases	70,939	69,735
Commercial Lending | Substandard
Credit quality
Loans and leases	82,836	51,856
Commercial Lending | Doubtful
Credit quality
Loans and leases	1,367	1,919
Commercial and Industrial
Credit quality
Loans and leases	3,331,092	3,239,600
Commercial and Industrial | Pass
Credit quality
Loans and leases	3,227,317	3,166,304
Commercial and Industrial | Special mention
Credit quality
Loans and leases	42,178	41,719
Commercial and Industrial | Substandard
Credit quality
Loans and leases	60,230	29,811
Commercial and Industrial | Doubtful
Credit quality
Loans and leases	1,367	1,766
Commercial Real Estate
Credit quality
Loans and leases	2,545,479	2,343,495
Commercial Real Estate | Pass
Credit quality
Loans and leases	2,501,783	2,298,839
Commercial Real Estate | Special mention
Credit quality
Loans and leases	22,351	23,859
Commercial Real Estate | Substandard
Credit quality
Loans and leases	21,345	20,797
Construction
Credit quality
Loans and leases	555,794	450,012
Construction | Pass
Credit quality
Loans and leases	548,893	445,149
Construction | Special mention
Credit quality
Loans and leases	5,821	3,789
Construction | Substandard
Credit quality
Loans and leases	1,080	1,074
Lease Financing
Credit quality
Loans and leases	180,676	180,040
Lease Financing | Pass
Credit quality
Loans and leases	179,906	179,345
Lease Financing | Special mention
Credit quality
Loans and leases	589	368
Lease Financing | Substandard
Credit quality
Loans and leases	181	174
Lease Financing | Doubtful
Credit quality
Loans and leases		153
Residential and consumer
Credit quality
Loans and leases	5,449,351	5,307,231
Residential and consumer | Performing
Credit quality
Loans and leases	5,415,305	5,265,885
Residential and consumer | Non-performing and delinquent
Credit quality
Loans and leases	34,046	41,346
Residential
Credit quality
Loans and leases	3,921,881	3,796,459
Residential | Performing
Credit quality
Loans and leases	3,907,274	3,778,070
Residential | Non-performing and delinquent
Credit quality
Loans and leases	14,607	18,389
Consumer
Credit quality
Loans and leases	1,527,470	1,510,772
Consumer loans | Consumer
Credit quality
Loans and leases	233,318	243,512
Consumer loans | Consumer | Performing
Credit quality
Loans and leases	230,121	240,185
Consumer loans | Consumer | Non-performing and delinquent
Credit quality
Loans and leases	3,197	3,327
Consumer - Auto | Consumer
Credit quality
Loans and leases	964,177	922,756
Consumer - Auto | Consumer | Performing
Credit quality
Loans and leases	951,329	906,829
Consumer - Auto | Consumer | Non-performing and delinquent
Credit quality
Loans and leases	12,848	15,927
Credit Cards | Consumer
Credit quality
Loans and leases	329,975	344,504
Credit Cards | Consumer | Performing
Credit quality
Loans and leases	326,581	340,801
Credit Cards | Consumer | Non-performing and delinquent
Credit quality
Loans and leases	$ 3,394	$ 3,703