Allowance for Loan Losses and Credit Quality of Loans, Past Due Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 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	$ 34,803	$ 38,067
Nonaccrual	25,174	25,487
Current	7,076,121	6,824,155
Recorded total loans	7,136,098	6,887,709
31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	25,610	26,641
61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	5,476	6,341
Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	3,717	5,085
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	3,444,266	3,222,310
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	2,246,676	2,284,563
Consumer Loans [Member] | Indirect Auto [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	1,193,635	1,216,144
Consumer Loans [Member] | Specialty Lending [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	542,063	524,928
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded total loans	1,445,156	1,380,836
Originated Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	32,917	36,515
Nonaccrual	23,581	23,372
Current	6,814,722	6,505,231
Recorded total loans	6,871,220	6,565,118
Originated Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	24,353	25,476
Originated Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	5,111	5,969
Originated Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	3,453	5,070
Originated Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	5,759	3,980
Nonaccrual	13,059	12,031
Current	3,310,182	3,062,609
Recorded total loans	3,329,000	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	5,597	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	162	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	0	588
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,227	909
Nonaccrual	1,177	1,062
Current	838,502	846,148
Recorded total loans	840,906	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	1,227	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	3,576	1,677
Nonaccrual	4,847	4,995
Current	1,941,143	1,734,558
Recorded total loans	1,949,566	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	3,576	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	0	588
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	956	1,394
Nonaccrual	7,035	5,974
Current	530,537	481,903
Recorded total loans	538,528	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	794	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	162	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	0	0
Originated Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	25,126	29,770
Nonaccrual	4,650	4,563
Current	2,193,167	2,218,606
Recorded total loans	2,222,943	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	17,577	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	4,759	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	2,790	3,300
Originated Loans [Member] | Consumer Loans [Member] | Indirect Auto [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	14,973	18,005
Nonaccrual	2,175	1,971
Current	1,176,487	1,196,136
Recorded total loans	1,193,635	1,216,112
Originated Loans [Member] | Consumer Loans [Member] | Indirect Auto [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	11,860	14,519
Originated Loans [Member] | Consumer Loans [Member] | Indirect Auto [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	2,108	2,300
Originated Loans [Member] | Consumer Loans [Member] | Indirect Auto [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,005	1,186
Originated Loans [Member] | Consumer Loans [Member] | Specialty Lending [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	6,547	6,814
Nonaccrual	0	0
Current	535,516	518,114
Recorded total loans	542,063	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	3,153	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	2,087	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	1,307	1,562
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	3,606	4,951
Nonaccrual	2,475	2,592
Current	481,164	504,356
Recorded total loans	487,245	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	2,564	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	564	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	478	552
Originated Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	2,032	2,765
Nonaccrual	5,872	6,778
Current	1,311,373	1,224,016
Recorded total loans	1,319,277	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	1,179	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	190	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	663	1,182
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,886	1,552
Nonaccrual	1,593	2,115
Current	261,399	318,924
Recorded total loans	264,878	322,591
Acquired Loans [Member] | 31-60 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	1,257	1,165
Acquired Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	365	372
Acquired Loans [Member] | Greater Than 90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	264	15
Acquired Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	833	754
Nonaccrual	382	390
Current	114,051	142,546
Recorded total loans	115,266	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	546	466
Acquired Loans [Member] | Commercial Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	287	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	149	0
Nonaccrual	0	0
Current	19,215	26,124
Recorded total loans	19,364	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	149	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	60,937	84,492
Recorded total loans	60,937	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	684	754
Nonaccrual	382	390
Current	33,899	31,930
Recorded total loans	34,965	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	397	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	287	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	194	210
Nonaccrual	105	227
Current	23,434	31,187
Recorded total loans	23,733	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	136	153
Acquired Loans [Member] | Consumer Loans [Member] | 61-90 Days Past Due Accruing [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total past due accruing	58	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] | Indirect Auto [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] | Indirect Auto [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] | Indirect Auto [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] | Indirect Auto [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	194	208
Nonaccrual	105	227
Current	23,434	31,157
Recorded total loans	23,733	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	136	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	58	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	859	588
Nonaccrual	1,106	1,498
Current	123,914	145,191
Recorded total loans	125,879	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	575	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	20	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	$ 264	$ 0