Calculation of Earnings Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 27, 2021	Feb. 29, 2020	Feb. 27, 2021	Feb. 29, 2020
Numerator for Basic and Diluted Earnings Per Share:
Net income (loss)	$ 228	$ (93)	$ (230)	$ (558)
Undistributed losses, Basic	(552)	(869)	(2,570)	(2,884)
Undistributed losses, Diluted	$ (552)	$ (869)	$ (2,570)	$ (2,884)
Denominator for Basic and Diluted Earnings Per Share:
Effect of dilutive securities dilutive stock options	72
Weighted Average Number of Shares Outstanding, Diluted	13,280	13,135	13,194	13,119
Basic
Numerator for Basic and Diluted Earnings Per Share:
Net income (loss)	$ 228	$ (93)	$ (230)	$ (558)
Diluted
Numerator for Basic and Diluted Earnings Per Share:
Net income (loss)	228	(93)	(230)	(558)
Common Stock
Numerator for Basic and Diluted Earnings Per Share:
Undistributed losses, Basic	(472)	(742)	(2,196)	(2,462)
Undistributed losses, Diluted	$ (472)	$ (742)	$ (2,196)	$ (2,462)
Denominator for Basic and Diluted Earnings Per Share:
Weighted Average Number of Shares Outstanding, Basic	11,111	11,038	11,097	11,022
Weighted Average Number of Shares Outstanding, Diluted	11,183	11,038	11,097	11,022
Net income (loss) per share:
Earnings Per Share, Basic	$ 0.02	$ (0.01)	$ (0.02)	$ (0.04)
Earnings Per Share, Diluted	$ 0.02	$ (0.01)	$ (0.02)	$ (0.04)
Common Stock | Basic
Numerator for Basic and Diluted Earnings Per Share:
Less dividends	$ 667	$ 662	$ 2,000	$ 1,986
Common Stock | Diluted
Numerator for Basic and Diluted Earnings Per Share:
Less dividends	667	662	2,000	1,986
Common Class B
Numerator for Basic and Diluted Earnings Per Share:
Undistributed losses, Basic	(80)	(127)	(374)	(422)
Undistributed losses, Diluted	$ (80)	$ (127)	$ (374)	$ (422)
Denominator for Basic and Diluted Earnings Per Share:
Weighted Average Number of Shares Outstanding, Basic	2,097	2,097	2,097	2,097
Weighted Average Number of Shares Outstanding, Diluted	2,097	2,097	2,097	2,097
Net income (loss) per share:
Earnings Per Share, Basic	$ 0.02	$ (0.01)	$ (0.02)	$ (0.04)
Earnings Per Share, Diluted	$ 0.02	$ (0.01)	$ (0.02)	$ (0.04)
Common Class B | Basic
Numerator for Basic and Diluted Earnings Per Share:
Less dividends	$ 113	$ 114	$ 340	$ 340
Common Class B | Diluted
Numerator for Basic and Diluted Earnings Per Share:
Less dividends	$ 113	$ 114	$ 340	$ 340