Note 6 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Feb. 28, 2016	Mar. 01, 2015	Feb. 28, 2016	Mar. 01, 2015	May. 31, 2015
Green Line [Member]
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount			$ (12,500,000)
Domestic Tax Authority [Member] | Earliest Tax Year [Member]
Open Tax Year			1997
State and Local Jurisdiction [Member] | Earliest Tax Year [Member]
Open Tax Year			1998
Effective Income Tax Rate Reconciliation, Percent			37.00%	36.00%
Income Tax Expense (Benefit)	$ (12,510,000)	$ 2,324,000	$ (9,750,000)	$ 5,409,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			35.00%
Unrecognized Tax Benefits	860,000		$ 860,000		$ 1,000,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 727,000		$ 727,000		$ 800,000