Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]
Balance at Dec. 31, 2013	$ 50,923	$ 50	$ 7	$ 41,498	$ 9,368
Balance, shares at Dec. 31, 2013		10	7,401
Issuance of common stock, net of issuance costs	15,989		$ 1	15,988
Issuance of common stock, net of issuance costs, shares			684
Exercise of stock options	$ 1,487			1,487
Exercise of stock options, shares	202		202
Issuance of restricted common stock, shares			283
Forfeiture of restricted common stock, shares			(38)
Purchase and retirement of common stock	$ (2,392)			(2,392)
Purchase and retirement of common stock, shares			(105)
Stock-based compensation	5,580			5,580
Tax impact from stock-based awards	(1,939)			(1,939)
Net loss	(15,820)				(15,820)
Cash dividends declared	(1,654)				(1,654)
Balance at Dec. 31, 2014	52,174	$ 50	$ 8	60,222	(8,106)
Balance, shares at Dec. 31, 2014		10	8,427
Issuance of common stock, net of issuance costs	12,896		$ 1	12,895
Issuance of common stock, net of issuance costs, shares			342
Exercise of stock options	$ 1,514			1,514
Exercise of stock options, shares	111		111
Issuance of restricted common stock, shares			150
Forfeiture of restricted common stock, shares			(31)
Purchase and retirement of common stock	$ (2,443)			(2,443)
Purchase and retirement of common stock, shares			(80)
Stock-based compensation	5,251			5,251
Net loss	(17,934)				(17,934)
Balance at Dec. 31, 2015	51,458	$ 50	$ 9	77,439	(26,040)
Balance, shares at Dec. 31, 2015		10	8,919
Issuance of common stock, net of issuance costs	39,700		$ 2	39,698
Issuance of common stock, net of issuance costs, shares			1,418
Exercise of stock options	$ 668			668
Exercise of stock options, shares	69		69
Issuance of restricted common stock, shares			212
Forfeiture of restricted common stock, shares			(12)
Purchase and retirement of common stock	$ (2,537)			(2,537)
Purchase and retirement of common stock, shares			(83)
Stock-based compensation	5,717			5,717
Net loss	(21,672)				(21,672)
Balance at Dec. 31, 2016	$ 73,334	$ 50	$ 11	$ 120,985	$ (47,712)
Balance, shares at Dec. 31, 2016		10	10,523