Annual report pursuant to Section 13 and 15(d)

Short-term Financing (Narrative) (Details)

v3.7.0.1
Short-term Financing (Narrative) (Details)
$ in Millions
 12 Months Ended
Jun. 01, 2017
USD ($)
May 31, 2017
USD ($)
loan
May 31, 2016
USD ($)
Line of Credit [Member]      
Line of Credit Facility [Line Items]      
Number of lines of credit | loan   4  
Amounts outstanding   $ 0.0 $ 0.0
Line of Credit [Member] | PNC Bank, National Association [Member]      
Line of Credit Facility [Line Items]      
Expiration date   Feb. 28, 2018  
Line of Credit [Member] | JP Morgan Chase Bank, N.A. [Member]      
Line of Credit Facility [Line Items]      
Expiration date   Feb. 28, 2018  
Standby Letters of Credit [Member]      
Line of Credit Facility [Line Items]      
Maximum borrowing capacity   $ 47.3 43.0
Amounts outstanding   $ 0.0 0.0
Standby Letters of Credit [Member] | Extended [Member] | Subsequent Event [Member]      
Line of Credit Facility [Line Items]      
Expiration date Jul. 01, 2018    
Revolving Credit Facility [Member] | PNC Bank, National Association [Member]      
Line of Credit Facility [Line Items]      
Expiration term   3 years  
Maximum borrowing capacity   $ 150.0  
Expiration date   Mar. 17, 2019  
Maximum amount borrowed   $ 55.6  
Weighted-average amount borrowed   $ 52.8  
Number of days borrowed   353 days  
Weighted-average interest rate   1.21%  
Amounts outstanding   $ 0.0 0.0
Revolving Credit Facility [Member] | PNC Bank, National Association [Member] | Subsequent Event [Member]      
Line of Credit Facility [Line Items]      
Amounts outstanding $ 55.0    
Revolving Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member]      
Line of Credit Facility [Line Items]      
Expiration term   5 years  
Maximum borrowing capacity   $ 1,000.0  
Expiration date   Aug. 05, 2020  
Maximum amount borrowed   $ 450.0 450.0
Weighted-average amount borrowed   $ 196.7 $ 305.0
Number of days borrowed   30 days 5 days
Weighted-average interest rate   2.89% 3.39%
Amounts outstanding   $ 0.0 $ 0.0
Revolving Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Seven Days [Member]      
Line of Credit Facility [Line Items]      
Maximum amount borrowed   $ 150.0  
Number of days borrowed   7 days  
Revolving Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Eighteen Days [Member]      
Line of Credit Facility [Line Items]      
Maximum amount borrowed   $ 50.0  
Number of days borrowed   18 days  
Revolving Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Seven And Eighteen Days [Member]      
Line of Credit Facility [Line Items]      
Weighted-average interest rate   1.40%  
Revolving Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Overnight Basis [Member] | Subsequent Event [Member]      
Line of Credit Facility [Line Items]      
Weighted-average amount borrowed $ 335.0    
Minimum [Member] | Standby Letters of Credit [Member]      
Line of Credit Facility [Line Items]      
Expiration date   Jul. 01, 2017  
Maximum [Member] | Standby Letters of Credit [Member]      
Line of Credit Facility [Line Items]      
Expiration date   May 01, 2018