Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2016	$ 73,334	$ 50	$ 11	$ 120,985	$ (47,712)
Balance, shares at Dec. 31, 2016		10	10,523
Exercise of stock options	177	$ 0	$ 0	177	0
Exercise of stock options, shares		0	19
Issuance of restricted common stock	0	$ 0	$ 0	0	0
Issuance of restricted common stock, shares		0	178
Forfeiture of restricted common stock	0	$ 0	$ 0	0	0
Forfeiture of restricted common stock, shares		0	(2)
Purchase and retirement of common stock	(583)	$ 0	$ 0	(583)	0
Purchase and retirement of common stock, shares		0	(23)
Stock-based compensation	1,548	$ 0	$ 0	1,573	(25)
Net loss	(6,218)	0	0	0	(6,218)
Balance at Mar. 31, 2017	68,258	$ 50	$ 11	122,152	(53,955)
Balance, shares at Mar. 31, 2017		10	10,695
Balance at Dec. 31, 2017	82,347	$ 50	$ 12	155,793	(73,508)
Balance, shares at Dec. 31, 2017		10	11,651
Exercise of stock options	$ 560	$ 0	$ 0	560	0
Exercise of stock options, shares	46	0	46
Issuance of restricted common stock	$ 0	$ 0	$ 0	0	0
Issuance of restricted common stock, shares		0	178
Forfeiture of restricted common stock	0	$ 0	$ 0	0	0
Forfeiture of restricted common stock, shares		0	(10)
Purchase and retirement of common stock	(528)	$ 0	$ 0	(528)	0
Purchase and retirement of common stock, shares		0	(18)
Stock-based compensation	1,715	$ 0	$ 0	1,715	0
Cumulative effect of the adoption of the new revenue standard, net of tax	139	0	0	0	139
Net loss	(8,112)	0	0	0	(8,112)
Balance at Mar. 31, 2018	$ 76,121	$ 50	$ 12	$ 157,540	$ (81,481)
Balance, shares at Mar. 31, 2018		10	11,847