Stockholders' Equity - Summary of common shareholders' equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			$ 28,165
Balance at December 31, 2017 (shares)			2,614,506
Net Income	$ 1,457	$ 671	$ 2,495	$ 802
Purchase of treasury shares			(150)
Cash dividend			(413)
Stock based compensation, net of tax benefit			183
Balance at June 30, 2018	$ 30,280		$ 30,280
Balance at June 30, 2018 (shares)	2,614,506		2,614,506
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			$ 523
Balance at December 31, 2017 (shares)			2,614,506
Net Income			$ 0
Purchase of treasury shares			0
Cash dividend			0
Stock based compensation, net of tax benefit			0
Balance at June 30, 2018	$ 523		$ 523
Balance at June 30, 2018 (shares)	2,614,506		2,614,506
Capital in excess of par value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			$ 14,171
Net Income			0
Purchase of treasury shares			0
Cash dividend			0
Stock based compensation, net of tax benefit			55
Balance at June 30, 2018	$ 14,226		14,226
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			15,709
Net Income			2,495
Purchase of treasury shares			0
Cash dividend			(413)
Stock based compensation, net of tax benefit			(6)
Balance at June 30, 2018	17,785		17,785
ESOT
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			(662)
Net Income			0
Purchase of treasury shares			0
Cash dividend			0
Stock based compensation, net of tax benefit			0
Balance at June 30, 2018	(662)		(662)
Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			(1,544)
Net Income			0
Purchase of treasury shares			(150)
Cash dividend			0
Stock based compensation, net of tax benefit			128
Balance at June 30, 2018	(1,566)		(1,566)
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			(32)
Net Income			0
Purchase of treasury shares			0
Cash dividend			0
Stock based compensation, net of tax benefit			6
Balance at June 30, 2018	$ (26)		$ (26)