Allowance for Loan Losses and Credit Quality of Loans, Troubled Debt Restructured Loans (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) Contract	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2018 USD ($) Contract	Sep. 30, 2017 USD ($) Contract
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract	8	6	25	23
Pre-modification outstanding recorded investment	$ 90	$ 714	$ 918	$ 5,235
Post-modification outstanding recorded investment	$ 89	$ 747	$ 918	$ 5,211
Number of contracts | Contract	22	19	54	46
Recorded Investment	$ 1,214	$ 1,181	$ 3,237	$ 2,691
Commercial Loans [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract			3	2
Pre-modification outstanding recorded investment			$ 369	$ 3,637
Post-modification outstanding recorded investment			$ 371	$ 3,572
Number of contracts | Contract			2	2
Recorded Investment			$ 258	$ 474
Commercial Loans [Member] | Commercial [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract				1
Pre-modification outstanding recorded investment				$ 3,300
Post-modification outstanding recorded investment				$ 3,239
Number of contracts | Contract			0	1
Recorded Investment			$ 0	$ 145
Commercial Loans [Member] | Business Banking [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract			3	1
Pre-modification outstanding recorded investment			$ 369	$ 337
Post-modification outstanding recorded investment			$ 371	$ 333
Number of contracts | Contract			2	1
Recorded Investment			$ 258	$ 329
Consumer Loans [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract	8	5	17	13
Pre-modification outstanding recorded investment	$ 90	$ 196	$ 226	$ 532
Post-modification outstanding recorded investment	$ 89	$ 229	$ 224	$ 571
Number of contracts | Contract	17	13	35	32
Recorded Investment	$ 816	$ 635	$ 1,740	$ 1,400
Consumer Loans [Member] | Indirect [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract		1		4
Pre-modification outstanding recorded investment		$ 7		$ 39
Post-modification outstanding recorded investment		$ 7		$ 37
Number of contracts | Contract	0	1	0	2
Recorded Investment	$ 0	$ 13	$ 0	$ 19
Consumer Loans [Member] | Dealer Finance [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract	8		15
Pre-modification outstanding recorded investment	$ 90		$ 185
Post-modification outstanding recorded investment	$ 89		$ 183
Consumer Loans [Member] | Home Equity [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract		4		8
Pre-modification outstanding recorded investment		$ 189		$ 373
Post-modification outstanding recorded investment		$ 222		$ 414
Number of contracts | Contract	0	12	0	30
Recorded Investment	$ 0	$ 622	$ 0	$ 1,381
Consumer Loans [Member] | Direct [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract			2	1
Pre-modification outstanding recorded investment			$ 41	$ 120
Post-modification outstanding recorded investment			$ 41	$ 120
Number of contracts | Contract	17	0	35	0
Recorded Investment	$ 816	$ 0	$ 1,740	$ 0
Residential Real Estate [Member]
Troubled Debt Restructured Loans [Abstract]
Number of contracts | Contract		1	5	8
Pre-modification outstanding recorded investment		$ 518	$ 323	$ 1,066
Post-modification outstanding recorded investment		$ 518	$ 323	$ 1,068
Number of contracts | Contract	5	6	17	12
Recorded Investment	$ 398	$ 546	$ 1,239	$ 817