Note 8 - Employee Post-employment Benefits (Tables)
 6 Months Ended
Dec. 01, 2015
Notes Tables  
Schedule of Net Benefit Costs [Table Text Block]
   
Pension Plans
 
   
Thirteen weeks ended
    
Twenty-six weeks ended
  
   
December 1,
    
December 2,
    
December 1,
    
December 2,
  
   
2015
    
2014
    
2015
    
2014
  
Service cost
   $ 42     $ 75     $ 272     $ 150  
Interest cost
     441       444       1,040       887  
Expected return on plan assets
     (102
)
     (125
)
     (205
)
     (249
)
Recognized actuarial loss
     473       430       1,101       860  
Net periodic benefit cost
   $ 854     $ 824     $ 2,208     $ 1,648  
   
Postretirement Medical and Life Benefits
  
   
Thirteen weeks ended
    
Twenty-six weeks ended
  
   
December 1,
    
December 2,
    
December 1,
    
December 2,
  
   
2015
    
2014
    
2015
    
2014
  
Service cost
   $ 1     $ 1     $ 2     $ 2  
Interest cost
     12       11       24       23  
Recognized actuarial loss
     33       34       65       67  
Net periodic benefit cost
   $ 46     $ 46     $ 91     $ 92