CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance (in shares) at Dec. 31, 2014		19,115,000
Balance at Dec. 31, 2014	$ 115,417	$ 96	$ 138,391	$ (312)	$ (22,758)
Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans, net of shares withheld for tax payments (in shares)		18,000
Issuance of shares under stock plans, net of shares withheld for tax payments	93	$ 0	93
Stock-based compensation, net of shares withheld for tax payments (in shares)		46,000
Stock-based compensation, net of shares withheld for tax payments	1,157	$ 0	1,157
Stock-based compensation, net of shares withheld for tax payments	44		44
Unrealized gain (loss) on derivative hedge transactions, net of tax	(40)			(40)
Tax payments related to stock-based awards and performance shares issued	151		(151)
Net income (loss)	2,218
Balance (in shares) at Dec. 31, 2015		19,179,000
Balance at Dec. 31, 2015	118,738	$ 96	139,534	(352)	(20,540)
Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans, net of shares withheld for tax payments (in shares)		20,000
Issuance of shares under stock plans, net of shares withheld for tax payments	172	$ 0	172
Stock-based compensation, net of shares withheld for tax payments (in shares)		62,000
Stock-based compensation, net of shares withheld for tax payments		$ 0	1,087
Unrealized gain (loss) on derivative hedge transactions, net of tax	90			90
Tax payments related to stock-based awards and performance shares issued	106		(106)
Net income (loss)	$ (320)
Balance (in shares) at Dec. 31, 2016	19,261,245	19,261,000
Balance at Dec. 31, 2016	$ 119,661	$ 96	140,687	(262)	(20,860)
Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans, net of shares withheld for tax payments (in shares)		25,000
Issuance of shares under stock plans, net of shares withheld for tax payments	219	$ 0	219
Stock-based compensation, net of shares withheld for tax payments (in shares)		24,000
Stock-based compensation, net of shares withheld for tax payments		$ 0	1,317
Unrealized gain (loss) on derivative hedge transactions, net of tax	98			98
Tax payments related to stock-based awards and performance shares issued	27		(27)
Net income (loss)	$ 9,523
Balance (in shares) at Dec. 31, 2017	19,309,829	19,310,000
Balance at Dec. 31, 2017	$ 130,791	$ 96	$ 142,196	$ (164)	$ (11,337)