Loans and Leases and the Allowance for Loan and Lease Losses (Aging Analysis) (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	$ 17,380	$ 11,574
Total Past Due and Non-Accrual	82,527	52,104
Current	10,908,365	10,396,670
Total Loans and Leases	10,990,892	10,448,774	$ 9,796,947
Non-Accrual Loans and Leases that are Current	$ 11,506	4,523
Number of days non-accrual loans and leases are not past due	30 days
30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 45,964	28,141
60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	10,777	5,822
Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	8,406	6,567
Commercial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	10,074	2,582
Total Past Due and Non-Accrual	26,626	6,924
Current	4,187,201	3,972,868
Total Loans and Leases	4,213,827	3,979,792	3,766,498
Non-Accrual Loans and Leases that are Current	9,665	2,555
Commercial | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	16,353	4,214
Commercial | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	199	118
Commercial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	10
Commercial | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	830	542
Total Past Due and Non-Accrual	13,512	4,323
Current	1,365,640	1,326,826
Total Loans and Leases	1,379,152	1,331,149
Non-Accrual Loans and Leases that are Current	421	515
Commercial | Commercial and Industrial | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	12,534	3,653
Commercial | Commercial and Industrial | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	148	118
Commercial | Commercial and Industrial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	10
Commercial | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	9,244	2,040
Total Past Due and Non-Accrual	12,242	2,601
Current	2,505,809	2,299,755
Total Loans and Leases	2,518,051	2,302,356
Non-Accrual Loans and Leases that are Current	9,244	2,040
Commercial | Commercial Mortgage | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,998	561
Commercial | Commercial Mortgage | 60 to 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	152	0
Current	194,018	170,061
Total Loans and Leases	194,170	170,061
Non-Accrual Loans and Leases that are Current	0	0
Commercial | Construction | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	101	0
Commercial | Construction | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	51	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	720	0
Current	121,734	176,226
Total Loans and Leases	122,454	176,226
Non-Accrual Loans and Leases that are Current	0	0
Commercial | Lease Financing | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	720	0
Commercial | Lease Financing | 60 to 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	7,306	8,992
Total Past Due and Non-Accrual	55,901	45,180
Current	6,721,164	6,423,802
Total Loans and Leases	6,777,065	6,468,982	$ 6,030,449
Non-Accrual Loans and Leases that are Current	1,841	1,968
Consumer | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	29,611	23,927
Consumer | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	10,578	5,704
Consumer | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	8,406	6,557
Consumer | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	4,125	5,321
Total Past Due and Non-Accrual	14,131	13,724
Current	3,876,969	3,660,072
Total Loans and Leases	3,891,100	3,673,796
Non-Accrual Loans and Leases that are Current	1,429	1,203
Consumer | Residential Mortgage | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,097	5,319
Consumer | Residential Mortgage | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,070	638
Consumer | Residential Mortgage | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,839	2,446
Consumer | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	3,181	3,671
Total Past Due and Non-Accrual	13,535	11,259
Current	1,662,538	1,670,183
Total Loans and Leases	1,676,073	1,681,442
Non-Accrual Loans and Leases that are Current	412	765
Consumer | Home Equity | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,949	3,323
Consumer | Home Equity | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,280	1,581
Consumer | Home Equity | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,125	2,684
Consumer | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	21,170	15,125
Current	699,116	643,008
Total Loans and Leases	720,286	658,133
Non-Accrual Loans and Leases that are Current	0	0
Consumer | Automobile | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	16,067	12,372
Consumer | Automobile | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,154	2,240
Consumer | Automobile | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	949	513
Consumer | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	7,065	5,072
Current	482,541	450,539
Total Loans and Leases	489,606	455,611
Non-Accrual Loans and Leases that are Current	0	0
Consumer | Other | 30 to 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,498	2,913
Consumer | Other | 60 to 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,074	1,245
Consumer | Other | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 1,493	$ 914