Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Unpaid Principal Balance
With no related allowance recorded	$ 2,630		$ 2,630		$ 1,474
With an allowance recorded	1,001		1,001		979
Total	3,631		3,631		2,453
Recorded Investment
With no related allowance recorded	2,630		2,630		1,474
With an allowance recorded	1,001		1,001		979
Total	3,631		3,631		2,453
Allowance for Loan Losses Allocated
Total	200		200		198
Average Recorded Investment
Total	3,643	$ 2,566	3,655	$ 2,593
Interest Income Recognized
Total	35	33	98	96
Cash Basis Interest Recognized
Total	25	32	55	95
Commercial
Average Recorded Investment
Total			105	235
Interest Income Recognized
Total			3	8
Cash Basis Interest Recognized
Total			2	8
Residential Real Estate
Average Recorded Investment
Total			222	757
Interest Income Recognized
Total			6	25
Cash Basis Interest Recognized
Total			4	24
Commercial | Commercial
Unpaid Principal Balance
With no related allowance recorded	103		103		53
With an allowance recorded					7
Recorded Investment
With no related allowance recorded	103		103		53
With an allowance recorded					7
Allowance for Loan Losses Allocated
Total					5
Average Recorded Investment
Total	104	229
Interest Income Recognized
Total	2	3
Cash Basis Interest Recognized
Total		3
Real estate | Residential Real Estate
Unpaid Principal Balance
With no related allowance recorded	149		149		837
With an allowance recorded	70		70
Recorded Investment
With no related allowance recorded	149		149		837
With an allowance recorded	70		70
Allowance for Loan Losses Allocated
Total	13		13
Average Recorded Investment
Total	220	751
Interest Income Recognized
Total	2	9
Cash Basis Interest Recognized
Total	1	8
Other | Commercial Real Estate
Unpaid Principal Balance
With no related allowance recorded	2,370		2,370		579
With an allowance recorded	931		931		954
Recorded Investment
With no related allowance recorded	2,370		2,370		579
With an allowance recorded	931		931		954
Allowance for Loan Losses Allocated
Total	187		187		192
Average Recorded Investment
Total	3,310	1,560	3,318	1,584
Interest Income Recognized
Total	31	21	88	62
Cash Basis Interest Recognized
Total	24	21	48	62
Other | Consumer
Unpaid Principal Balance
With no related allowance recorded	8		8		5
Recorded Investment
With no related allowance recorded	8		8		5
With an allowance recorded					18
Allowance for Loan Losses Allocated
Total					$ 1
Average Recorded Investment
Total	$ 9	$ 26	10	17
Interest Income Recognized
Total			1	1
Cash Basis Interest Recognized
Total			$ 1	$ 1