Shareholders' Equity - Summary of common shareholders' equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock	Capital in excess of par value	Retained earnings	ESOT	Treasury stock	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2014	$ 523	$ 14,068	$ 9,176	$ (964)	$ (1,909)	$ (14)	$ 20,880
Balance (shares) at Dec. 31, 2014	2,614,506						2,614,506
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			2,771				2,771
Purchase of treasury shares					(114)		(114)
Stock based compensation		11			79		90
Balance at Mar. 31, 2015	$ 523	$ 14,079	$ 11,947	$ (964)	$ (1,944)	$ (14)	$ 23,627	[1]
Balance (shares) at Mar. 31, 2015	2,614,506						2,614,506	[1]

[1] Unaudited