Loans and Leases and the Allowance for Credit Losses - Schedule of Aging Analysis by Class of Loan and Lease Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	$ 16,294	$ 17,380
Total Past Due and Non-Accrual	39,472	82,527
Current	11,754,136	10,908,365
Total Loans and Leases	11,793,608	10,990,892
Non-Accrual Loans and Leases that are Current	10,301	11,506
30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	10,168	45,964
60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,418	10,777
Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	9,592	8,406
Commercial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	9,090	10,074
Total Past Due and Non-Accrual	9,357	26,626
Current	5,007,510	4,187,201
Total Loans and Leases	5,016,867	4,213,827
Non-Accrual Loans and Leases that are Current	8,905	9,665
Commercial | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	475	830
Total Past Due and Non-Accrual	742	13,512
Current	1,907,740	1,365,640
Total Loans and Leases	1,908,482	1,379,152
Non-Accrual Loans and Leases that are Current	290	421
Commercial | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	8,615	9,244
Total Past Due and Non-Accrual	8,615	12,242
Current	2,736,996	2,505,809
Total Loans and Leases	2,745,611	2,518,051
Non-Accrual Loans and Leases that are Current	8,615	9,244
Commercial | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	0	152
Current	250,943	194,018
Total Loans and Leases	250,943	194,170
Non-Accrual Loans and Leases that are Current	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	720
Current	111,831	121,734
Total Loans and Leases	111,831	122,454
Non-Accrual Loans and Leases that are Current	0	0
Commercial | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	220	16,353
Commercial | 30 - 59 Days Past Due | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	220	12,534
Commercial | 30 - 59 Days Past Due | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	2,998
Commercial | 30 - 59 Days Past Due | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	101
Commercial | 30 - 59 Days Past Due | Lease Financing
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	720
Commercial | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	47	199
Commercial | 60 - 89 Days Past Due | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	47	148
Commercial | 60 - 89 Days Past Due | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | 60 - 89 Days Past Due | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	51
Commercial | 60 - 89 Days Past Due | Lease Financing
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Past Due 90 Days or More | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Past Due 90 Days or More | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Past Due 90 Days or More | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | Past Due 90 Days or More | Lease Financing
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	7,204	7,306
Total Past Due and Non-Accrual	30,115	55,901
Current	6,746,626	6,721,164
Total Loans and Leases	6,776,741	6,777,065
Non-Accrual Loans and Leases that are Current	1,396	1,841
Consumer | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	2,764	7,065
Current	414,326	482,541
Total Loans and Leases	417,090	489,606
Non-Accrual Loans and Leases that are Current	0	0
Consumer | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	3,543	4,125
Total Past Due and Non-Accrual	14,428	14,131
Current	4,029,800	3,876,969
Total Loans and Leases	4,044,228	3,891,100
Non-Accrual Loans and Leases that are Current	0	1,429
Consumer | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	3,661	3,181
Total Past Due and Non-Accrual	9,879	13,535
Current	1,595,607	1,662,538
Total Loans and Leases	1,605,486	1,676,073
Non-Accrual Loans and Leases that are Current	1,396	412
Consumer | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	3,044	21,170
Current	706,893	699,116
Total Loans and Leases	709,937	720,286
Non-Accrual Loans and Leases that are Current	0	0
Consumer | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	9,948	29,611
Consumer | 30 - 59 Days Past Due | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,856	3,498
Consumer | 30 - 59 Days Past Due | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,695	6,097
Consumer | 30 - 59 Days Past Due | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,628	3,949
Consumer | 30 - 59 Days Past Due | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,769	16,067
Consumer | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,371	10,578
Consumer | 60 - 89 Days Past Due | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	650	2,074
Consumer | 60 - 89 Days Past Due | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,583	2,070
Consumer | 60 - 89 Days Past Due | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,019	2,280
Consumer | 60 - 89 Days Past Due | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	119	4,154
Consumer | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	9,592	8,406
Consumer | Past Due 90 Days or More | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	258	1,493
Consumer | Past Due 90 Days or More | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	6,607	1,839
Consumer | Past Due 90 Days or More | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,571	4,125
Consumer | Past Due 90 Days or More | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 156	$ 949