Allowance for Loan and Lease Losses - Credit Risk Profiles (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) factor	Dec. 31, 2018 USD ($)
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	$ 13,264,609	$ 13,076,191
Loss
Credit quality
Loans and leases	0	0
Commercial Lending
Credit quality
Loans and leases	7,087,011	6,974,069
Commercial Lending | Pass
Credit quality
Loans and leases	6,783,065	6,718,416
Commercial Lending | Special mention
Credit quality
Loans and leases	218,662	149,733
Commercial Lending | Substandard
Credit quality
Loans and leases	85,284	105,728
Commercial Lending | Doubtful
Credit quality
Loans and leases		192
Commercial and Industrial
Credit quality
Loans and leases	3,177,844	3,208,760
Commercial and Industrial | Pass
Credit quality
Loans and leases	3,048,463	3,069,546
Commercial and Industrial | Special mention
Credit quality
Loans and leases	90,410	57,012
Commercial and Industrial | Substandard
Credit quality
Loans and leases	38,971	82,010
Commercial and Industrial | Doubtful
Credit quality
Loans and leases		192
Commercial Real Estate
Credit quality
Loans and leases	3,194,219	2,990,783
Commercial Real Estate | Pass
Credit quality
Loans and leases	3,021,877	2,876,907
Commercial Real Estate | Special mention
Credit quality
Loans and leases	127,097	91,298
Commercial Real Estate | Substandard
Credit quality
Loans and leases	45,245	22,578
Construction
Credit quality
Loans and leases	549,578	626,757
Construction | Pass
Credit quality
Loans and leases	548,480	625,607
Construction | Special mention
Credit quality
Loans and leases	171	200
Construction | Substandard
Credit quality
Loans and leases	927	950
Lease Financing
Credit quality
Loans and leases	165,370	147,769
Lease Financing | Pass
Credit quality
Loans and leases	164,245	146,356
Lease Financing | Special mention
Credit quality
Loans and leases	984	1,223
Lease Financing | Substandard
Credit quality
Loans and leases	141	190
Residential and consumer
Credit quality
Loans and leases	6,177,598	6,102,122
Residential and consumer | Performing
Credit quality
Loans and leases	6,130,326	6,040,469
Residential and consumer | Non-performing and delinquent
Credit quality
Loans and leases	47,272	61,653
Residential Mortgage.
Credit quality
Loans and leases	3,618,433	3,527,101
Residential Mortgage. | Performing
Credit quality
Loans and leases	3,609,720	3,519,172
Residential Mortgage. | Non-performing and delinquent
Credit quality
Loans and leases	8,713	7,929
Home Equity Line
Credit quality
Loans and leases	908,452	912,517
Home Equity Line | Performing
Credit quality
Loans and leases	903,257	903,284
Home Equity Line | Non-performing and delinquent
Credit quality
Loans and leases	5,195	9,233
Consumer
Credit quality
Loans and leases	1,650,713	1,662,504
Consumer loans | Consumer
Credit quality
Loans and leases	237,264	239,906
Consumer loans | Consumer | Performing
Credit quality
Loans and leases	231,355	234,458
Consumer loans | Consumer | Non-performing and delinquent
Credit quality
Loans and leases	5,909	5,448
Consumer - Auto | Consumer
Credit quality
Loans and leases	1,082,943	1,078,132
Consumer - Auto | Consumer | Performing
Credit quality
Loans and leases	1,060,248	1,044,393
Consumer - Auto | Consumer | Non-performing and delinquent
Credit quality
Loans and leases	22,695	33,739
Credit Cards | Consumer
Credit quality
Loans and leases	330,506	344,466
Credit Cards | Consumer | Performing
Credit quality
Loans and leases	325,746	339,162
Credit Cards | Consumer | Non-performing and delinquent
Credit quality
Loans and leases	$ 4,760	$ 5,304