Business Segment Reporting - Sales by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 29, 2020	Nov. 24, 2019	Nov. 29, 2020	Nov. 24, 2019
Segment Reporting Information [Line Items]
Product sales	$ 130,904	$ 142,593	$ 266,547	$ 281,307
Canada
Segment Reporting Information [Line Items]
Product sales	13,700	18,400	30,200	39,100
Belgium
Segment Reporting Information [Line Items]
Product sales	2,800	3,100	6,700	3,100
Czech Republic
Segment Reporting Information [Line Items]
Product sales	1,200	0	1,700	0
Ireland
Segment Reporting Information [Line Items]
Product sales	400	1,100	1,200	2,500
All Other Countries
Segment Reporting Information [Line Items]
Product sales	$ 1,600	$ 2,000	$ 2,800	$ 3,400