Allowance for Loan Losses and Credit Quality of Loans, Past Due Loans (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Aging [Abstract]
Minimum number of days past due for nonaccrual loan status	90 days
Total past due accruing	$ 39,808	$ 38,067
Nonaccrual	24,623	25,487
Current	6,949,378	6,824,155
Recorded total loans	7,013,809	6,887,709
31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	26,300	26,641
61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	5,166	6,341
Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	8,342	5,085
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	3,351,201	3,222,310
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	2,245,688	2,284,563
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	1,416,920	1,380,836
Originated Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	37,876	36,515
Nonaccrual	23,022	23,372
Current	6,663,222	6,505,231
Recorded total loans	6,724,120	6,565,118
Originated Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	24,477	25,476
Originated Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	5,123	5,969
Originated Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	8,276	5,070
Originated Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	11,488	3,980
Nonaccrual	11,917	12,031
Current	3,194,985	3,062,609
Recorded total loans	3,218,390	3,078,620
Originated Loans [Member] | Commercial Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	6,269	3,090
Originated Loans [Member] | Commercial Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	313	302
Originated Loans [Member] | Commercial Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	4,906	588
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	505	909
Nonaccrual	729	1,062
Current	836,593	846,148
Recorded total loans	837,827	848,119
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	505	909
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Originated Loans [Member] | Commercial Loans [Member] | CRE [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	8,485	1,677
Nonaccrual	4,664	4,995
Current	1,832,708	1,734,558
Recorded total loans	1,845,857	1,741,230
Originated Loans [Member] | Commercial Loans [Member] | CRE [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	3,646	1,089
Originated Loans [Member] | Commercial Loans [Member] | CRE [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Originated Loans [Member] | Commercial Loans [Member] | CRE [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	4,839	588
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	2,498	1,394
Nonaccrual	6,524	5,974
Current	525,684	481,903
Recorded total loans	534,706	489,271
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	2,118	1,092
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	313	302
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	67	0
Originated Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	24,206	29,770
Nonaccrual	4,794	4,563
Current	2,191,267	2,218,606
Recorded total loans	2,220,267	2,252,939
Originated Loans [Member] | Consumer Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	16,626	20,960
Originated Loans [Member] | Consumer Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	4,710	5,510
Originated Loans [Member] | Consumer Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	2,870	3,300
Originated Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	14,226	18,005
Nonaccrual	2,241	1,971
Current	1,179,316	1,196,136
Recorded total loans	1,195,783	1,216,112
Originated Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	11,167	14,519
Originated Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,965	2,300
Originated Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,094	1,186
Originated Loans [Member] | Consumer Loans [Member] | Specialty Lending [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	6,904	6,814
Nonaccrual	0	0
Current	521,601	518,114
Recorded total loans	528,505	524,928
Originated Loans [Member] | Consumer Loans [Member] | Specialty Lending [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	3,681	3,479
Originated Loans [Member] | Consumer Loans [Member] | Specialty Lending [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,655	1,773
Originated Loans [Member] | Consumer Loans [Member] | Specialty Lending [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,568	1,562
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	3,076	4,951
Nonaccrual	2,553	2,592
Current	490,350	504,356
Recorded total loans	495,979	511,899
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,778	2,962
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,090	1,437
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	208	552
Originated Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	2,182	2,765
Nonaccrual	6,311	6,778
Current	1,276,970	1,224,016
Recorded total loans	1,285,463	1,233,559
Originated Loans [Member] | Residential Real Estate [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,582	1,426
Originated Loans [Member] | Residential Real Estate [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	100	157
Originated Loans [Member] | Residential Real Estate [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	500	1,182
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,932	1,552
Nonaccrual	1,601	2,115
Current	286,156	318,924
Recorded total loans	289,689	322,591
Acquired Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,823	1,165
Acquired Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	43	372
Acquired Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	66	15
Acquired Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	445	754
Nonaccrual	366	390
Current	132,000	142,546
Recorded total loans	132,811	143,690
Acquired Loans [Member] | Commercial Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	445	466
Acquired Loans [Member] | Commercial Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	288
Acquired Loans [Member] | Commercial Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | C&I [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Nonaccrual	0	0
Current	28,823	26,124
Recorded total loans	28,823	26,124
Acquired Loans [Member] | Commercial Loans [Member] | C&I [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | C&I [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | C&I [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | CRE [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Nonaccrual	0	0
Current	67,853	84,492
Recorded total loans	67,853	84,492
Acquired Loans [Member] | Commercial Loans [Member] | CRE [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | CRE [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | CRE [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Commercial Loans [Member] | Business Banking [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	445	754
Nonaccrual	366	390
Current	35,324	31,930
Recorded total loans	36,135	33,074
Acquired Loans [Member] | Commercial Loans [Member] | Business Banking [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	445	466
Acquired Loans [Member] | Commercial Loans [Member] | Business Banking [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	288
Acquired Loans [Member] | Commercial Loans [Member] | Business Banking [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	0
Acquired Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	319	210
Nonaccrual	131	227
Current	24,971	31,187
Recorded total loans	25,421	31,624
Acquired Loans [Member] | Consumer Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	276	153
Acquired Loans [Member] | Consumer Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	43	42
Acquired Loans [Member] | Consumer Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	15
Acquired Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing		2
Nonaccrual		0
Current		30
Recorded total loans		32
Acquired Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing		1
Acquired Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing		1
Acquired Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing		0
Acquired Loans [Member] | Consumer Loans [Member] | Direct [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	319	208
Nonaccrual	131	227
Current	24,971	31,157
Recorded total loans	25,421	31,592
Acquired Loans [Member] | Consumer Loans [Member] | Direct [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	276	152
Acquired Loans [Member] | Consumer Loans [Member] | Direct [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	43	41
Acquired Loans [Member] | Consumer Loans [Member] | Direct [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	15
Acquired Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,168	588
Nonaccrual	1,104	1,498
Current	129,185	145,191
Recorded total loans	131,457	147,277
Acquired Loans [Member] | Residential Real Estate [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,102	546
Acquired Loans [Member] | Residential Real Estate [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	0	42
Acquired Loans [Member] | Residential Real Estate [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	$ 66	$ 0