Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2015		$ 7	$ 54,829	$ 132,431		$ (2,290)
Beginning Balance (shares) at Dec. 31, 2015		7,111,338				292,855
Common stock issuance under Employee Stock Purchase Plan			151
Common stock issuance under Employee Stock Purchase Plan (shares)		17,268
Capital investment		$ 1	500
Capital investment, (shares)		73,207
Tax impact on RSUs vested and options exercised or forfeited			(488)
Share-based compensation			1,405
Share-based compensation (shares)		13,486
Net gain (loss) on derivative instruments					$ 21
Net income (loss)	$ (5,347)			(5,347)
Ending Balance at Dec. 31, 2016		$ 8	56,397	127,084	21	$ (2,290)
Ending Balance (shares) at Dec. 31, 2016		7,215,299				292,855
Common stock issuance under Employee Stock Purchase Plan			226
Common stock issuance under Employee Stock Purchase Plan (shares)		16,185
Exercise of stock options			327
Exercise of stock options (shares)		22,125
Share-based compensation			1,564
Share-based compensation (shares)		4,178
Net gain (loss) on derivative instruments					(114)
Retroactive adoption of ASU 2016-09				835
Net income (loss)	7,610			7,610
Ending Balance at Dec. 31, 2017	$ 191,668	$ 8	58,514	135,529	(93)	$ (2,290)
Ending Balance (shares) at Dec. 31, 2017		7,257,787				292,855
Common stock issuance under Employee Stock Purchase Plan			149
Common stock issuance under Employee Stock Purchase Plan (shares)		7,922
Exercise of stock options			716
Exercise of stock options (shares)	48,075	50,770
Public offering		$ 1	32,246
Public offering (shares)		1,408,163
Capital investment			33
Share-based compensation			1,442
Share-based compensation (shares)		27,848
Net gain (loss) on derivative instruments					94
Net income (loss)	$ 10,662			10,662
Ending Balance at Dec. 31, 2018	$ 237,011	$ 9	$ 93,100	$ 146,191	$ 1	$ (2,290)
Ending Balance (shares) at Dec. 31, 2018		8,752,490				292,855