Loans and Allowance for Loan Losses - Non-accrual loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	$ 3,270	$ 3,751
Transfer into non-accrual	3,494	1,483
Transfer to OREO	(705)
Loans paid down/payoffs	(3,235)	(947)
Loans return to accrual status	(448)	(452)
Loans charged off	(1,134)	(565)
Balance	1,947	3,270
Consumer
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	185	403
Transfer into non-accrual	290	10
Loans paid down/payoffs	(27)	(130)
Loans return to accrual status	(58)
Loans charged off	(204)	(98)
Balance	186	185
Residential Real estate
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	2,124	2,508
Transfer into non-accrual	246	329
Loans paid down/payoffs	(633)	(429)
Loans return to accrual status	(192)	(281)
Loans charged off	(589)	(3)
Balance	956	2,124
Indirect
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	88	193
Transfer into non-accrual	636	686
Loans paid down/payoffs	(132)	(163)
Loans return to accrual status	(135)	(171)
Loans charged off	(341)	(457)
Balance	116	88
Commercial Mortgage Portfolio Segment
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	48
Transfer into non-accrual	27	56
Loans paid down/payoffs	(48)	(1)
Loans charged off		(7)
Balance	27	48
Construction
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	318
Transfer into non-accrual		402
Loans paid down/payoffs	(318)	(84)
Balance		318
Commercial Real Estate
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	507	647
Transfer into non-accrual	2,295
Loans paid down/payoffs	(2,077)	(140)
Loans return to accrual status	(63)
Balance	$ 662	$ 507