Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Capital in Excess of Par	Retained Earnings
Beginning Balance, Value at Dec. 31, 2017	$ 21,181	$ 1,189	$ 6,441	$ 13,551
Beginning Balance, Shares at Dec. 31, 2017	11,886	11,886
Stock-based compensation, Value	$ 60		60
Stock options exercised, Value	88	$ 14	74
Stock options exercised, Shares		138
Net income (loss)	(196)			(196)
Ending Balance, Value at Mar. 31, 2018	21,133	$ 1,203	6,575	13,355
Ending Balance, Shares at Mar. 31, 2018		12,024
Beginning Balance, Value at Dec. 31, 2017	$ 21,181	$ 1,189	6,441	13,551
Beginning Balance, Shares at Dec. 31, 2017	11,886	11,886
Net income (loss)	$ 2,155
Ending Balance, Value at Sep. 30, 2018	23,967	$ 1,241	7,020	15,706
Ending Balance, Shares at Sep. 30, 2018		12,408
Beginning Balance, Value at Mar. 31, 2018	21,133	$ 1,203	6,575	13,355
Beginning Balance, Shares at Mar. 31, 2018		12,024
Stock-based compensation, Value	61		61
Net income (loss)	1,284			1,284
Ending Balance, Value at Jun. 30, 2018	$ 22,478	$ 1,203	6,636	14,639
Ending Balance, Shares at Jun. 30, 2018	12,024	12,024
Stock-based compensation, Value	$ 63		63
Stock options exercised, Value	359	$ 38	321
Stock options exercised, Shares		384
Net income (loss)	1,067			1,067
Ending Balance, Value at Sep. 30, 2018	23,967	$ 1,241	7,020	15,706
Ending Balance, Shares at Sep. 30, 2018		12,408
Beginning Balance, Value at Dec. 31, 2018	$ 24,082	$ 1,241	7,063	15,778
Beginning Balance, Shares at Dec. 31, 2018	12,408	12,408
Stock-based compensation, Value	$ 42		42
Net income (loss)	(330)			(330)
Ending Balance, Value at Mar. 31, 2019	23,794	$ 1,241	7,105	15,448
Ending Balance, Shares at Mar. 31, 2019		12,408
Beginning Balance, Value at Dec. 31, 2018	$ 24,082	$ 1,241	7,063	15,778
Beginning Balance, Shares at Dec. 31, 2018	12,408	12,408
Net income (loss)	$ (659)
Ending Balance, Value at Sep. 30, 2019	$ 23,585	$ 1,246	7,220	15,119
Ending Balance, Shares at Sep. 30, 2019	12,462	12,462
Beginning Balance, Value at Mar. 31, 2019	$ 23,794	$ 1,241	7,105	15,448
Beginning Balance, Shares at Mar. 31, 2019		12,408
Stock-based compensation, Value	42		42
Stock options exercised, Value	41	$ 5	36
Stock options exercised, Shares		51
Net income (loss)	(716)			(716)
Ending Balance, Value at Jun. 30, 2019	$ 23,161	$ 1,246	7,183	14,732
Ending Balance, Shares at Jun. 30, 2019	12,460	12,459
Stock-based compensation, Value	$ 35		35
Stock options exercised, Value	2		2
Stock options exercised, Shares		3
Net income (loss)	387			387
Ending Balance, Value at Sep. 30, 2019	$ 23,585	$ 1,246	$ 7,220	$ 15,119
Ending Balance, Shares at Sep. 30, 2019	12,462	12,462