Note 8 - Employee Post-employment Benefits (Details Textual)
$ in Thousands
 3 Months Ended
Aug. 11, 2016
Aug. 30, 2016
USD ($)
Sep. 01, 2015
USD ($)
May 31, 2016
USD ($)
Pension Plan [Member] | Payroll and Related Costs [Member]        
Defined Benefit Pension Plan Liabilities, Current   $ 2,500   $ 2,500
Pension Plan [Member] | Other Deferred Liabilities [Member]        
Defined Benefit Pension Plan, Liabilities, Noncurrent   34,700   35,700
Pension Plan [Member]        
Defined Benefit Plan, Amortization of Gains (Losses)   (338) $ (628)  
Post-retirement Medical and Life Benefits Plans [Member] | Payroll and Related Costs [Member]        
Defined Benefit Pension Plan Liabilities, Current   100   100
Post-retirement Medical and Life Benefits Plans [Member] | Other Deferred Liabilities [Member]        
Defined Benefit Pension Plan, Liabilities, Noncurrent   1,000   1,000
Retirement Plan [Member]        
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year   100    
Selling, General and Administrative Expense [Member] | Employee Severance [Member]        
Closures and Impairments Expenses   300    
Employee Severance [Member]        
Employee-related Liabilities, Current   300   300
Closures and Impairments Expenses   1,700    
Selling, General and Administrative Expenses [Member]        
Defined Benefit Plan, Amortization of Gains (Losses)   400 700  
Employee-related Liabilities, Current   $ 14,978   $ 14,561
Defined Benefit Pension Plans   3    
Number of Restaurants Closed 95 99    
Closures and Impairments Expenses   $ 30,192 $ 2,712