Allowance for Loan Losses and Credit Quality of Loans, Credit Quality by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Credit Quality by Loan Class [Abstract]
Net Loans	$ 7,136,098	$ 6,887,709
Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,246,676	2,284,563
Consumer Credit Exposure [Member] | Indirect Auto [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,193,635	1,216,144
Consumer Credit Exposure [Member] | Specialty Lending [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	542,063	524,928
Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,445,156	1,380,836
Originated Loans [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	6,871,220	6,565,118
Originated Loans [Member] | Commercial Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,790,472	2,589,349
Originated Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,651,441	2,478,108
Originated Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	58,899	25,242
Originated Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	79,626	85,999
Originated Loans [Member] | Commercial Credit Exposure [Member] | Doubtful [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	506
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	840,906	848,119
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	782,763	796,778
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	28,380	11,348
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	29,257	39,993
Originated Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Doubtful [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	506
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,949,566	1,741,230
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,868,678	1,681,330
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	30,519	13,894
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	50,369	46,006
Originated Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Doubtful [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	0
Originated Loans [Member] | Business Banking Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	538,528	489,271
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	524,725	476,052
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	13,803	13,219
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	538,528	489,271
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	524,725	476,052
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	13,803	13,219
Originated Loans [Member] | Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,222,943	2,252,939
Originated Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,215,503	2,245,076
Originated Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	7,440	7,863
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,193,635	1,216,112
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,190,455	1,212,955
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	3,180	3,157
Originated Loans [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	542,063	524,928
Originated Loans [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	540,756	523,366
Originated Loans [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,307	1,562
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	487,245	511,899
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	484,292	508,755
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,953	3,144
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,319,277	1,233,559
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,312,742	1,225,599
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	6,535	7,960
Originated Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,319,277	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	1,312,742	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	6,535	7,960
Acquired Loans [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	264,878	322,591
Acquired Loans [Member] | Commercial Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	80,301	110,616
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	78,346	107,045
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,269	2,923
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	686	648
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	19,364	26,124
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	17,801	23,283
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,269	2,831
Acquired Loans [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	294	10
Acquired Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	60,937	84,492
Acquired Loans [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	60,545	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	392	638
Acquired Loans [Member] | Business Banking Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	34,965	33,074
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	32,030	29,945
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,935	3,129
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	34,965	33,074
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	32,030	29,945
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	2,935	3,129
Acquired Loans [Member] | Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	23,733	31,624
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	23,628	31,382
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	105	242
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member]
Credit Quality by Loan Class [Abstract]
Net Loans		32
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans		32
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect Auto [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	23,733	31,592
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	23,628	31,350
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	105	242
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	125,879	147,277
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	124,509	145,779
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	1,370	1,498
Acquired Loans [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member]
Credit Quality by Loan Class [Abstract]
Net Loans	125,879	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	124,509	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	$ 1,370	$ 1,498