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, 2016		$ 8	$ 56,397	$ 127,084	$ 21	$ (2,290)
Beginning 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	$ 7,610			7,610
Ending Balance at Dec. 31, 2017		$ 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)		50,770
Public offering		$ 1	32,246
Public offering (shares)		1,408,163
Share-based compensation			1,442
Share-based compensation (shares)		27,848
Capital investment			33
Net gain (loss) on derivative instruments					94
Net income	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
Common stock issuance under Employee Stock Purchase Plan			418
Common stock issuance under Employee Stock Purchase Plan (shares)		31,376
Exercise of stock options			53
Exercise of stock options (shares)	5,325	5,325
Share-based compensation			1,411			$ (21)
Share-based compensation (shares)		10,245				1,424
Net gain (loss) on derivative instruments					(11)
Adoption of ASU 2018-02	$ (21)			21	(21)
Net income	4,275			4,275
Ending Balance at Dec. 31, 2019	$ 243,136	$ 9	$ 94,982	$ 150,487	$ (31)	$ (2,311)
Ending Balance (shares) at Dec. 31, 2019		8,799,436				294,279