Note 10 - Share-based Employee Compensation - Summary of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Jun. 06, 2017	May 31, 2016
Granted, Shares (in shares)		0
Stock Options Services-Based [Member]
Outstanding, Shares (in shares)	2,066,000
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 7.89
Granted, Shares (in shares)	1,126,000
Granted, Weighted Average Exercise Price (in dollars per share)	$ 3.46
Cancellations and Forfeitures, Shares (in shares)	(50,000)
Cancellations and Forfeitures, Weighted Average Exercise Price (in dollars per share)	$ 4.49
Expired, Shares (in shares)	(1,448,000)
Expired, Weighted Average Exercise Price (in dollars per share)	$ 6.66
Outstanding, Shares (in shares)	1,694,000	2,066,000
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.09	$ 7.89
Outstanding (Year)	2 years 339 days
Exercisable at end of year (in shares)	1,224,000
Exercisable at end of year (in dollars per share)	$ 7
Exercisable at end of year (Year)	1 year 262 days