Allowance for Loan Losses and Credit Quality of Loans, Credit Quality by Loan Class (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Credit Quality by Loan Class [Abstract]
Net loans	$ 6,963,273	$ 6,887,709
Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,234,130	2,284,563
Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,404,079	1,380,836
Originated Loans [Member]
Credit Quality by Loan Class [Abstract]
Net loans	6,658,359	6,565,118
Originated Loans [Member] | Commercial Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,702,259	2,589,349
Originated Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,550,017	2,478,108
Originated Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans	63,924	25,242
Originated Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans	88,318	85,999
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member]
Credit Quality by Loan Class [Abstract]
Net loans	869,756	848,119
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans	799,988	796,778
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans	30,012	11,348
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans	39,756	39,993
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,832,503	1,741,230
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,750,029	1,681,330
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans	33,912	13,894
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans	48,562	46,006
Originated Loans [Member] | Business Banking Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	483,095	489,271
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	469,380	476,052
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	13,715	13,219
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member]
Credit Quality by Loan Class [Abstract]
Net loans	483,095	489,271
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	469,380	476,052
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	13,715	13,219
Originated Loans [Member] | Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,206,548	2,252,939
Originated Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,199,794	2,245,076
Originated Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	6,754	7,863
Originated Loans [Member] | Consumer Credit Exposure [Member] | Dealer Finance [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,189,670	1,216,112
Originated Loans [Member] | Consumer Credit Exposure [Member] | Dealer Finance [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,187,192	1,212,955
Originated Loans [Member] | Consumer Credit Exposure [Member] | Dealer Finance [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,478	3,157
Originated Loans [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member]
Credit Quality by Loan Class [Abstract]
Net loans	519,974	524,928
Originated Loans [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	518,493	523,366
Originated Loans [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,481	1,562
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member]
Credit Quality by Loan Class [Abstract]
Net loans	496,904	511,899
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	494,109	508,755
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,795	3,144
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,266,457	1,233,559
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,259,987	1,225,599
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	6,470	7,960
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,266,457	1,233,559
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,259,987	1,225,599
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	6,470	7,960
Acquired Loans [Member]
Credit Quality by Loan Class [Abstract]
Net loans	304,914	322,591
Acquired Loans [Member] | Commercial Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	109,401	110,616
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans	104,247	107,045
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,686	2,923
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans	3,468	648
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member]
Credit Quality by Loan Class [Abstract]
Net loans	33,039	26,124
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans	28,479	23,283
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,686	2,831
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,874	10
Acquired Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member]
Credit Quality by Loan Class [Abstract]
Net loans	76,362	84,492
Acquired Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans	75,768	83,762
Acquired Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans	0	92
Acquired Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans	594	638
Acquired Loans [Member] | Business Banking Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	30,309	33,074
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	27,482	29,945
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,827	3,129
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member]
Credit Quality by Loan Class [Abstract]
Net loans	30,309	33,074
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	27,482	29,945
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans	2,827	3,129
Acquired Loans [Member] | Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	27,582	31,624
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	27,466	31,382
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	116	242
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Dealer Finance [Member]
Credit Quality by Loan Class [Abstract]
Net loans		32
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Dealer Finance [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		32
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Dealer Finance [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		0
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member]
Credit Quality by Loan Class [Abstract]
Net loans	27,582	31,592
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	27,466	31,350
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	116	242
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans	137,622	147,277
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	136,272	145,779
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	1,350	1,498
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member]
Credit Quality by Loan Class [Abstract]
Net loans	137,622	147,277
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans	136,272	145,779
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans	$ 1,350	$ 1,498