Quarterly Consolidated Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	May 26, 2019	Feb. 24, 2019	Nov. 25, 2018	Aug. 26, 2018	May 27, 2018	Feb. 25, 2018	Nov. 26, 2017	Aug. 27, 2017	May 26, 2019	May 27, 2018	May 28, 2017
Condensed Financial Information Disclosure [Abstract]
Revenues	$ 152,780	$ 155,554	$ 124,557	$ 124,668	$ 141,076	$ 144,909	$ 122,461	$ 115,781	$ 557,559	$ 524,227
Gross profit	26,212	21,569	16,885	16,337	24,809	19,806	14,921	18,802	81,003	78,338	$ 79,212
Net income (loss) from continuing operations	367	1,533	(113)	335	6,711	16,281	414	2,355	2,122	25,761	10,135
Net income (loss) applicable to common stockholders	$ (262)	$ 1,067	$ (584)	$ 190	$ 6,108	$ 16,088	$ 487	$ 2,146	$ 411	$ 24,829	$ 10,590
Net income per basic share from continuing operations (in dollars per share)	$ 0.01	$ 0.05	$ 0.00	$ 0.01	$ 0.24	$ 0.59	$ 0.02	$ 0.08	$ 0.07	$ 0.93	$ 0.37
Net income per diluted share from continuing operations (in dollars per share)	$ 0.01	$ 0.05	$ 0.00	$ 0.01	$ 0.24	$ 0.58	$ 0.02	$ 0.08	$ 0.07	$ 0.92	$ 0.36