Consolidated Statements of Equity - USD ($) $ in Thousands		Total	Common Stock [Member]		Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings (Accumulated Deficit) [Member]	Temporary Equity [Member]	L Catterton [Member]	L Catterton [Member] Additional Paid-in Capital [Member]	L Catterton [Member] Temporary Equity [Member]	Mill Road Capital II, L.P. [Member]	Mill Road Capital II, L.P. [Member] Common Stock [Member]	Mill Road Capital II, L.P. [Member] Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding (in shares)			30,138,672		2,423,871
Beginning balance, shares at Dec. 29, 2015			30,138,672		2,423,871
Beginning balance at Dec. 29, 2015		$ 93,772	$ 301		$ (35,000)	$ 120,634	$ (134)	$ 7,971
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock options (in shares)	[1]		162,253
Issuance of stock options		1,100	$ 2	[1]		1,098
Stock-based compensation expense		2,540				2,540
Net loss		(71,677)						(71,677)
Other comprehensive income (loss)		83					83
Ending balance at Jan. 03, 2017		25,818	$ 303	[1],[2]	$ (35,000)	124,272	(51)	(63,706)
Ending balance, shares at Jan. 03, 2017			30,300,925	[1]	2,423,871
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding (in shares)			30,138,672		2,423,871
Shares outstanding (in shares)			30,300,925	[1]	2,423,871
Issuance of stock options (in shares)			123,291	[1]										8,873,240
Issuance of stock options		83	$ 1	[1]		82				$ 6,056	$ 6,056	$ 10,533	$ 29,110	$ 89	$ 29,021
Conversion of preferred stock to L Catterton (in shares)			4,252,873
Conversion of preferred stock to L Catterton		18,500	$ 43			18,457			$ (18,500)
Accretion of preferred stock		7,967				7,967			$ 7,967
Stock-based compensation expense		1,692				1,692
Net loss		(37,482)						(37,482)
Other comprehensive income (loss)		51					51
Ending balance at Jan. 02, 2018		35,861	$ 436		$ (35,000)	171,613	0	(101,188)
Ending balance, shares at Jan. 02, 2018			43,550,329		2,423,871
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding (in shares)			30,300,925	[1]	2,423,871
Shares outstanding (in shares)			43,550,329		2,423,871
Issuance of stock options (in shares)			2,500,000
Issuance of stock options		22,992	$ 25			22,967
Shares issued	[1]		302,980
Stock Issued During Period, Value, Employee Stock Purchase Plan		749	$ 3	[1]		746
Stock-based compensation expense		3,026				3,026
Net loss		(8,441)						(8,441)
Ending balance at Jan. 01, 2019		$ 52,681	$ 464		$ (35,000)	$ 198,352	$ 0	$ (111,135)
Ending balance, shares at Jan. 01, 2019			46,353,309		2,423,871
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding (in shares)			43,550,329		2,423,871
Shares outstanding (in shares)			46,353,309		2,423,871

[1] Unless otherwise noted, activity relates to Class A common stock

[2] 1,522,098 shares of Class B common stock