Note 14 - Quarterly Financial Data (Unaudited) - Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 30, 2017	[1],[2]	Sep. 30, 2017	[1]	Jul. 01, 2017	[1]	Apr. 01, 2017	[1]	Dec. 31, 2016	[1]	Sep. 24, 2016	[1]	Jun. 25, 2016	[1]	Mar. 26, 2016	[1]	Dec. 30, 2017		Dec. 31, 2016		Dec. 26, 2015
Revenue, Net	$ 84,090		$ 93,651		$ 93,866		$ 81,097		$ 70,694		$ 69,259		$ 76,353		$ 65,778		$ 352,704		$ 282,084	[1]	$ 269,654
Gross profit	34,423		36,909		37,130		32,256		25,527	[3]	23,280	[3]	26,739	[3]	19,282	[3]	140,718		94,828	[3]
Income (loss) from continuing operations	6,895		8,755		10,708		6,763		2,306	[3]	128	[3]	2,517	[3]	(1,691)	[3]	33,121		3,260	[3]	5,792
Net income (loss)	$ 6,895		$ 8,755		$ 10,430		$ 6,763		$ 2,089	[3]	$ 179	[3]	$ 2,462	[3]	$ (1,691)	[3]	$ 32,843		$ 3,039	[3]	$ 250
Income from continuing operations (in dollars per share)	$ 0.24	[4]	$ 0.31	[4]	$ 0.39	[4]	$ 0.25	[4]	$ 0.09	[3],[4]	$ 0.01	[3],[4]	$ 0.09	[3],[4]	$ (0.06)	[3],[4]	$ 1.19	[4]	$ 0.12	[3],[4]	$ 0.22
Net income (in dollars per share)	0.24	[4]	0.31	[4]	0.38	[4]	0.25	[4]	0.08	[3],[4]	0.01	[3],[4]	0.09	[3],[4]	(0.06)	[3],[4]	1.18	[4]	0.11	[3],[4]	0.01
Income (loss) from continuing operations (in dollars per share)	0.23	[4]	0.30	[4]	0.37	[4]	0.24	[4]	0.08	[3],[4]	0.01	[3],[4]	0.09	[3],[4]	(0.06)	[3],[4]	1.15	[4]	0.12	[3],[4]	0.22
Net income (loss) (in dollars per share)	$ 0.23	[4]	$ 0.30	[4]	$ 0.36	[4]	$ 0.24	[4]	$ 0.08	[3],[4]	$ 0.01	[3],[4]	$ 0.09	[3],[4]	$ (0.06)	[3],[4]	$ 1.14	[4]	$ 0.11	[3],[4]	$ 0.01

[1] All quarters presented above were comprised of 13 weeks, except for the fourth quarter ended December 31, 2016 which was comprised of 14 weeks.

[2] The fourth quarter of 2017 includes impact of Tax Act enacted in December 2017.

[3] As a result of the adoption of ASU 2016-09, in the fourth quarter of 2016, certain amounts in the first three quarters have been restated as if the new accounting guidance was adopted starting with the first day of our 2016 fiscal year. The impact of these restatements was not significant.

[4] The sum of the four quarters may not agree to the year total due to rounding within a quarter and the inclusion or exclusion of common stock equivalents.