CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balances at Dec. 27, 2014	$ 289,436	$ 57	$ 711,676	$ (1,761)	$ (420,536)
Balances (in shares) at Dec. 27, 2014		56,518,428
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to exercise of options for cash	209		209
Issuance of common stock pursuant to exercise of options for cash (in shares)		24,607
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld (in shares)		1,993,603
Issuance of common stock under the Employee Stock Purchase Plan	3,206	$ 0	3,206
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		565,493
Purchase and retirement of common stock	(8,211)	$ (1)	(8,210)
Purchase and retirement of common stock (in shares)		(1,013,162)
Stock-based compensation	12,023		12,023
Stock-based compensation
Components of other comprehensive income:	(64)			(64)
Foreign currency translation adjustments	(397)			(397)
Currency translation adjustments	0
Net Income (loss)	(1,523)				(1,523)
Balances at Dec. 26, 2015	294,681	$ 58	718,904	(2,222)	(422,059)
Balances (in shares) at Dec. 26, 2015		58,088,969
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to exercise of options for cash	2,003		2,003
Issuance of common stock pursuant to exercise of options for cash (in shares)		232,190
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Issuance of common stock pursuant to vesting of restricted stock units, net of stock withheld (in shares)		1,579,218
Issuance of common stock under the Employee Stock Purchase Plan	3,741	$ 1	3,740
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		557,281
Purchase and retirement of common stock	97,079	$ 10	97,069
Purchase and retirement of common stock (in shares)		10,450,189
Stock-based compensation	11,625		11,625
Stock-based compensation
Components of other comprehensive income:	29			29
Foreign currency translation adjustments	(2,042)			(2,042)
Currency translation adjustments	495			495
Net Income (loss)	(6,557)				(6,557)
Balances at Dec. 31, 2016	401,056	$ 71	833,341	(3,740)	(428,616)
Balances (in shares) at Dec. 31, 2016		70,907,847
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to exercise of options for cash	13,837	$ 1	13,836
Stock Issued During Period, Shares, Restricted Stock Award, Gross		1,364,612
Stock Issued During Period, Value, Restricted Stock Award, Gross	1	$ 1
Issuance of common stock pursuant to exercise of options for cash (in shares)		1,473,389
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited		(502,016)
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	(6,886)		(6,886)
Issuance of common stock under the Employee Stock Purchase Plan	5,695	$ 1	5,694
Issuance of common stock under the Employee Stock Purchase Plan (in shares)		655,961
Purchase and retirement of common stock	18,970	$ (1)	(18,969)
Purchase and retirement of common stock (in shares)		(1,367,617)
Stock-based compensation	16,230		16,230
ASU 2016-09 Adjustment			(130)		130
Stock-based compensation
Components of other comprehensive income:	(206)			(206)
Foreign currency translation adjustments	6,764			6,764
Currency translation adjustments	203			203
Net Income (loss)	40,913				40,913
Balances at Dec. 30, 2017	$ 458,637	$ 73	$ 843,116	$ 3,021	$ (387,573)
Balances (in shares) at Dec. 30, 2017	72,532,176