Stockholders' Equity - Summary of common shareholders' equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	$ 28,165
Net Income	331	$ 26
Purchase of treasury shares	(117)
Balance at March 31, 2018	$ 28,379
Balance at March 31, 2018 (shares)	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
Balance at March 31, 2018	$ 523
Balance at March 31, 2018 (shares)	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
Balance at March 31, 2018	14,171
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	15,709
Net Income	331
Purchase of treasury shares	0
Balance at March 31, 2018	16,040
ESOT
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	(662)
Net Income	0
Purchase of treasury shares	0
Balance at March 31, 2018	(662)
Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	(1,544)
Net Income	0
Purchase of treasury shares	(117)
Balance at March 31, 2018	(1,661)
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
Balance at March 31, 2018	$ (32)