Loans and Leases and the Allowance for Loan and Lease Losses (Aging Analysis) (Details 4) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	$ 18,706	$ 11,574
Total Past Due and Non-Accrual	55,563	52,104
Current	10,825,735	10,396,670
Total Loans and Leases	10,881,298	10,448,774	$ 10,231,062
Non-Accrual Loans and Leases that are Current	$ 13,260	4,523
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	$ 24,004	28,141
60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,762	5,822
Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,091	6,567
Commercial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	11,661	2,582
Total Past Due and Non-Accrual	13,449	6,924
Current	4,143,284	3,972,868
Total Loans and Leases	4,156,733	3,979,792	3,900,308
Non-Accrual Loans and Leases that are Current	11,536	2,555
Commercial | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,576	4,214
Commercial | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	131	118
Commercial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	81	10
Commercial | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	573	542
Total Past Due and Non-Accrual	1,611	4,323
Current	1,359,400	1,326,826
Total Loans and Leases	1,361,011	1,331,149
Non-Accrual Loans and Leases that are Current	448	515
Commercial | Commercial and Industrial | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	826	3,653
Commercial | Commercial and Industrial | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	131	118
Commercial | Commercial and Industrial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	81	10
Commercial | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	11,088	2,040
Total Past Due and Non-Accrual	11,838	2,601
Current	2,465,458	2,299,755
Total Loans and Leases	2,477,296	2,302,356
Non-Accrual Loans and Leases that are Current	11,088	2,040
Commercial | Commercial Mortgage | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	750	561
Commercial | Commercial Mortgage | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	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	154,754	170,061
Total Loans and Leases	154,754	170,061
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	163,672	176,226
Total Loans and Leases	163,672	176,226
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	7,045	8,992
Total Past Due and Non-Accrual	42,114	45,180
Current	6,682,451	6,423,802
Total Loans and Leases	6,724,565	6,468,982	$ 6,330,754
Non-Accrual Loans and Leases that are Current	1,724	1,968
Consumer | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	22,428	23,927
Consumer | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,631	5,704
Consumer | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,010	6,557
Consumer | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	4,258	5,321
Total Past Due and Non-Accrual	10,935	13,724
Current	3,835,576	3,660,072
Total Loans and Leases	3,846,511	3,673,796
Non-Accrual Loans and Leases that are Current	782	1,203
Consumer | Residential Mortgage | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,666	5,319
Consumer | Residential Mortgage | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	979	638
Consumer | Residential Mortgage | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,032	2,446
Consumer | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	2,787	3,671
Total Past Due and Non-Accrual	9,712	11,259
Current	1,672,239	1,670,183
Total Loans and Leases	1,681,951	1,681,442
Non-Accrual Loans and Leases that are Current	942	765
Consumer | Home Equity | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,446	3,323
Consumer | Home Equity | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,159	1,581
Consumer | Home Equity | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,320	2,684
Consumer | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	16,072	15,125
Current	697,352	643,008
Total Loans and Leases	713,424	658,133
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	13,809	12,372
Consumer | Automobile | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,681	2,240
Consumer | Automobile | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	582	513
Consumer | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	5,395	5,072
Current	477,284	450,539
Total Loans and Leases	482,679	455,611
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	2,507	2,913
Consumer | Other | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,812	1,245
Consumer | Other | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 1,076	$ 914