Consolidated Statements of Equity Statement - 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]	Class B Common Stock [Member]
Beginning balance at Jan. 01, 2013		$ 10,407	$ 232	[1],[2]	$ 0	$ 7,585	$ (24)	$ 2,614
Beginning balance, shares at Jan. 01, 2013			23,238,984	[2]	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with IPO, net of transaction expenses		100,069	$ 62	[2]		100,007
Issuance of common stock, net of transaction expenses, shares	[2]		6,160,714
Elimination of temporary equity at IPO		3,601				2,572		1,029
Proceeds from exercise of stock options, warrants and employee stock purchase plan		1,982	$ 1	[2]		1,981
Proceeds from exercise of stock options, warrants and employee stock purchase plan, shares	[2]		144,907
Treasury shares acquired		(2,777)			$ (2,777)
Treasury shares acquired, shares					65,478
Stock-based compensation expenses		201				201
2010 Merger-transaction expenses		1,098				1,098
Stock-based compensation expense related to acceleration of vesting		3,203				3,203
Other		24					24
Other, shares	[2]		(48)
Net (loss) income		6,665						6,665
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0
Ending balance at Dec. 31, 2013		124,473	$ 295	[1],[2]	$ (2,777)	116,647	0	10,308
Ending balance, shares at Dec. 31, 2013			29,544,557	[2]	65,478
Temporary equity, beginning balance at Jan. 01, 2013		3,601
Increase (Decrease) in Temporary Equity [Roll Forward]
Elimination of temporary equity at IPO		(3,601)
Temporary equity related to put options		0
Temporary equity, ending balance at Dec. 31, 2013		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from exercise of stock options, warrants and employee stock purchase plan		2,676	$ 3	[2]		2,673
Proceeds from exercise of stock options, warrants and employee stock purchase plan, shares	[2]		275,783
Treasury shares acquired		(71)			$ (71)
Treasury shares acquired, shares					2,108
Stock-based compensation expenses		253				253
2010 Merger-transaction expenses		1,418				1,418
Other		(62)
Other, shares	[2]		0
Adjustments to Additional Paid in Capital, Other						(62)
Net (loss) income		11,428						11,428
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0
Ending balance at Dec. 30, 2014		140,115	$ 298	[1],[2]	$ (2,848)	120,929	0	21,736
Ending balance, shares at Dec. 30, 2014			29,820,340	[2]	68,000				6,292,640
Temporary equity, ending balance at Dec. 30, 2014		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from exercise of stock options, warrants and employee stock purchase plan		952	$ 3	[2]		949
Proceeds from exercise of stock options, warrants and employee stock purchase plan, shares	[2]		318,332
Treasury shares acquired		(35,000)			$ (32,152)	2,848
Treasury shares acquired, shares					2,356,285
2010 Merger-transaction expenses		1,698				1,698
Net (loss) income		(13,765)						(13,765)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(134)					(134)
Ending balance at Dec. 29, 2015		93,772	$ 301	[1],[2]	$ (35,000)	$ 120,634	$ (134)	$ 7,971
Ending balance, shares at Dec. 29, 2015			30,138,672	[2]	2,424,000				1,522,098
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity related to put options		0
Temporary equity, ending balance at Dec. 29, 2015		$ 0

[1] Includes 1,522,098 shares of Class B common stock as of December 29, 2015 and December 30, 2014 and 6,292,640 shares of Class B common stock as of December 31, 2013

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