Loans and Leases and the Allowance for Credit Losses - Schedule of Aging Analysis by Class of Loan and Lease Portfolio (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	$ 15,551	$ 16,149
Total Past Due and Non-Accrual	55,418	52,619
Current	12,085,285	11,887,401
Total Loans and Leases	12,140,703	11,940,020
Non-Accrual Loans and Leases that are Current	6,502	8,355
30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	21,548	16,577
60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	7,903	9,347
Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	10,416	10,546
Commercial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	8,796	8,968
Total Past Due and Non-Accrual	12,273	9,218
Current	5,247,098	5,091,468
Total Loans and Leases	5,259,371	5,100,686
Non-Accrual Loans and Leases that are Current	5,216	5,268
Commercial | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	293	441
Total Past Due and Non-Accrual	3,770	691
Current	2,010,211	1,874,602
Total Loans and Leases	2,013,981	1,875,293
Non-Accrual Loans and Leases that are Current	257	285
Commercial | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	8,503
Total Past Due and Non-Accrual	8,503
Current	2,850,743
Total Loans and Leases	2,859,246
Non-Accrual Loans and Leases that are Current	4,959
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	281,164	259,798
Total Loans and Leases	281,164	259,798
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	0
Current	104,980	110,766
Total Loans and Leases	104,980	110,766
Non-Accrual Loans and Leases that are Current	0	0
Commercial | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	8,503	8,527
Total Past Due and Non-Accrual		8,527
Current		2,846,302
Total Loans and Leases	2,859,246	2,854,829
Non-Accrual Loans and Leases that are Current		4,983
Commercial | 30 - 59 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,398	191
Commercial | 30 - 59 Days Past Due | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,398	191
Commercial | 30 - 59 Days Past Due | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0
Commercial | 30 - 59 Days Past Due | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | 30 - 59 Days Past Due | Lease Financing
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | 30 - 59 Days Past Due | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due		0
Commercial | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	70	59
Commercial | 60 - 89 Days Past Due | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	70	59
Commercial | 60 - 89 Days Past Due | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0
Commercial | 60 - 89 Days Past Due | Construction
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | 60 - 89 Days Past Due | Lease Financing
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	0	0
Commercial | 60 - 89 Days Past Due | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due		0
Commercial | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	9	0
Commercial | Past Due 90 Days or More | Commercial and Industrial
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	9	0
Commercial | Past Due 90 Days or More | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	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
Commercial | Past Due 90 Days or More | Commercial Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due		0
Consumer
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	6,755	7,181
Total Past Due and Non-Accrual	43,145	43,401
Current	6,838,187	6,795,933
Total Loans and Leases	6,881,332	6,839,334
Non-Accrual Loans and Leases that are Current	1,286	3,087
Consumer | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	6,715	5,328
Current	369,734	390,155
Total Loans and Leases	376,449	395,483
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	1,804	3,223
Total Past Due and Non-Accrual	12,494	14,629
Current	4,204,482	4,115,884
Total Loans and Leases	4,216,976	4,130,513
Non-Accrual Loans and Leases that are Current	404	2,100
Consumer | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	4,951	3,958
Total Past Due and Non-Accrual	16,753	13,946
Current	1,560,747	1,590,592
Total Loans and Leases	1,577,500	1,604,538
Non-Accrual Loans and Leases that are Current	882	987
Consumer | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Non-Accrual	0	0
Total Past Due and Non-Accrual	7,183	9,498
Current	703,224	699,302
Total Loans and Leases	710,407	708,800
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	18,150	16,386
Consumer | 30 - 59 Days Past Due | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,650	2,556
Consumer | 30 - 59 Days Past Due | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,510	4,049
Consumer | 30 - 59 Days Past Due | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,568	3,423
Consumer | 30 - 59 Days Past Due | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	5,422	6,358
Consumer | 60 - 89 Days Past Due
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	7,833	9,288
Consumer | 60 - 89 Days Past Due | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,237	1,612
Consumer | 60 - 89 Days Past Due | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	3,111	2,083
Consumer | 60 - 89 Days Past Due | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	2,328	3,378
Consumer | 60 - 89 Days Past Due | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	1,157	2,215
Consumer | Past Due 90 Days or More
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	10,407	10,546
Consumer | Past Due 90 Days or More | Other
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	828	1,160
Consumer | Past Due 90 Days or More | Residential Mortgage
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,069	5,274
Consumer | Past Due 90 Days or More | Home Equity
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	4,906	3,187
Consumer | Past Due 90 Days or More | Automobile
Aging Analysis of Accruing and Non-Accruing Loans and Leases
Days Past Due	$ 604	$ 925