Loans and Leases and the Allowance for Loan and Lease Losses (Aging Analysis) (Details 4) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	$ 28,153	$ 27,771
Total Past Due and Non-Accrual	67,909	64,184
Current	7,621,863	6,833,405
Total Loans and Leases	7,689,772	6,897,589	$ 6,606,350
Non-Accrual Loans and Leases that are Current	$ 5,506	8,826
Number of days non-accrual loans are not past due	30 days
30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 23,284	20,096
60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	8,327	7,656
Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	8,145	8,661
Commercial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	9,590	9,833
Total Past Due and Non-Accrual	15,810	11,641
Current	3,107,435	2,816,487
Total Loans and Leases	3,123,245	2,828,128	2,728,924
Non-Accrual Loans and Leases that are Current	1,404	7,819
Commercial | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,830	1,450
Commercial | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,390	356
Commercial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	2
Commercial | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	8,532	9,088
Total Past Due and Non-Accrual	14,723	10,438
Current	1,155,094	1,044,805
Total Loans and Leases	1,169,817	1,055,243
Non-Accrual Loans and Leases that are Current	571	7,819
Commercial | Commercial and Industrial | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,830	992
Commercial | Commercial and Industrial | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,361	356
Commercial | Commercial and Industrial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	2
Commercial | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	1,058	745
Total Past Due and Non-Accrual	1,087	1,203
Current	1,621,032	1,436,310
Total Loans and Leases	1,622,119	1,437,513
Non-Accrual Loans and Leases that are Current	833	0
Commercial | Commercial Mortgage | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	458
Commercial | Commercial Mortgage | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	29	0
Commercial | Commercial Mortgage | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	0	0
Current	129,254	109,183
Total Loans and Leases	129,254	109,183
Non-Accrual Loans and Leases that are Current	0	0
Commercial | Construction | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Construction | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Construction | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Lease Financing
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	0	0
Current	202,055	226,189
Total Loans and Leases	202,055	226,189
Non-Accrual Loans and Leases that are Current	0	0
Commercial | Lease Financing | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Lease Financing | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Lease Financing | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Consumer
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	18,563	17,938
Total Past Due and Non-Accrual	52,099	52,543
Current	4,514,428	4,016,918
Total Loans and Leases	4,566,527	4,069,461	$ 3,877,426
Non-Accrual Loans and Leases that are Current	4,102	1,007
Consumer | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	18,454	18,646
Consumer | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,937	7,300
Consumer | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	8,145	8,659
Consumer | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	14,749	14,841
Total Past Due and Non-Accrual	27,358	26,361
Current	2,848,247	2,544,729
Total Loans and Leases	2,875,605	2,571,090
Non-Accrual Loans and Leases that are Current	2,419	632
Consumer | Residential Mortgage | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,023	4,907
Consumer | Residential Mortgage | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,526	2,107
Consumer | Residential Mortgage | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	5,060	4,506
Consumer | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	3,814	3,097
Total Past Due and Non-Accrual	9,886	11,815
Current	983,931	854,873
Total Loans and Leases	993,817	866,688
Non-Accrual Loans and Leases that are Current	1,683	375
Consumer | Home Equity | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,331	3,461
Consumer | Home Equity | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,345	2,661
Consumer | Home Equity | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,396	2,596
Consumer | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	10,070	9,961
Current	357,570	313,887
Total Loans and Leases	367,640	323,848
Non-Accrual Loans and Leases that are Current	0	0
Consumer | Automobile | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	7,827	7,862
Consumer | Automobile | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,612	1,483
Consumer | Automobile | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	631	616
Consumer | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	4,785	4,406
Current	324,680	303,429
Total Loans and Leases	329,465	307,835
Non-Accrual Loans and Leases that are Current	0	0
Consumer | Other | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,273	2,416
Consumer | Other | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,454	1,049
Consumer | Other | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 1,058	$ 941