Stockholders' Equity - Summary of common shareholders' equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			$ 523
Balance (shares)			2,614,506
Net income
Purchase of treasury shares
Cash dividend
Stock based compensation, net of tax benefit
Balance	$ 523		$ 523
Balance (shares)	2,614,506		2,614,506
Capital in excess of par value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			$ 14,092
Net income
Purchase of treasury shares
Cash dividend
Stock based compensation, net of tax benefit			34
Balance	$ 14,126		14,126
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			13,395
Net income			1,262
Purchase of treasury shares
Cash dividend			(380)
Stock based compensation, net of tax benefit
Balance	14,277		14,277
ESOT
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			(863)
Net income
Purchase of treasury shares
Cash dividend
Stock based compensation, net of tax benefit
Balance	(863)		(863)
Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			(1,702)
Net income
Purchase of treasury shares			(165)
Cash dividend
Stock based compensation, net of tax benefit			206
Balance	(1,661)		(1,661)
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			(3)
Net income
Purchase of treasury shares
Cash dividend
Stock based compensation, net of tax benefit
Balance	(3)		(3)
Balance			25,442
Net income	1,004	$ 621	1,262	$ 3,392
Purchase of treasury shares			(165)
Cash dividend			(380)
Stock based compensation, net of tax benefit			240
Balance	$ 26,399		$ 26,399
Balance (shares)	2,614,506		2,614,506