Note 12 - Quarterly Consolidated Financial Information (Unaudited) - Summary of Unaudited Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	May 28, 2017	Feb. 26, 2017	Nov. 27, 2016	Aug. 28, 2016	May 29, 2016	Feb. 28, 2016	Nov. 29, 2015	Aug. 30, 2015	May 31, 2015	Mar. 01, 2015	Nov. 30, 2014	Aug. 31, 2014	May 28, 2017	May 29, 2016	May 31, 2015
Revenues	$ 127,430	$ 136,568	$ 135,865	$ 132,394	$ 135,313	$ 129,990	$ 140,441	$ 135,355	$ 134,448	$ 138,530	$ 132,665	$ 133,614	$ 532,257	$ 541,099	$ 539,257
Gross profit	19,657	23,432	18,953	21,144	22,784	12,931	17,265	17,977	18,668	16,885	15,666	14,188	83,186	70,957	65,407
Net income (loss)	$ 2,452	$ 3,500	$ 1,326	$ 3,312	$ 4,729	$ (21,190)	$ 1,868	$ 2,952	$ 4,196	$ 3,772	$ 3,223	$ 2,353	$ 10,590	$ (11,641)	$ 13,544
Net income (loss) per basic share (in dollars per share)	$ 0.09	$ 0.13	$ 0.05	$ 0.12	$ 0.17	$ (0.78)	$ 0.07	$ 0.11	$ 0.16	$ 0.14	$ 0.12	$ 0.09	$ 0.39	$ (0.43)	$ 0.50
Net income (loss) per diluted share (in dollars per share)	$ 0.09	$ 0.13	$ 0.05	$ 0.12	$ 0.17	$ (0.78)	$ 0.07	$ 0.11	$ 0.15	$ 0.14	$ 0.12	$ 0.09	$ 0.38	$ (0.43)	$ 0.50