Quarterly report pursuant to Section 13 or 15(d)

Short-term Financing (Narrative) (Details)

v3.10.0.1
Short-term Financing (Narrative) (Details) - USD ($)
$ in Millions
3 Months Ended
Sep. 01, 2018
Aug. 31, 2018
Aug. 31, 2017
May 31, 2018
Revolving Credit Facility [Member] | JPM $1 Billion Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member]        
Line of Credit Facility [Line Items]        
Amounts outstanding   $ 0.0   $ 0.0
Amount borrowed   $ 394.5 $ 660.0  
Number of days borrowed   6 days 13 days  
Weighted-average interest rate   4.99% 4.23%  
Weighted-average amount borrowed   $ 216.3 $ 278.8  
Revolving Credit Facility [Member] | JPM $1 Billion Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Three Days [Member]        
Line of Credit Facility [Line Items]        
Amount borrowed     $ 100.0  
Number of days borrowed     3 days  
Weighted-average interest rate     4.25%  
Revolving Credit Facility [Member] | JPM $1 Billion Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Two Overnight Basis [Member] | Subsequent Event [Member]        
Line of Credit Facility [Line Items]        
Weighted-average amount borrowed $ 417.0      
Revolving Credit Facility [Member] | JPM $500 Million Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member]        
Line of Credit Facility [Line Items]        
Amounts outstanding   0.0   0.0
Amount borrowed   $ 223.0    
Number of days borrowed   4 days    
Weighted-average interest rate   4.99% 0.00%  
Weighted-average amount borrowed   $ 133.4    
Revolving Credit Facility [Member] | JPM $500 Million Credit Facility [Member] | JP Morgan Chase Bank, N.A. [Member] | Overnight Basis [Member] | Subsequent Event [Member]        
Line of Credit Facility [Line Items]        
Amount borrowed $ 135.5      
Revolving Credit Facility [Member] | PNC $150 Million Credit Facility [Member] | PNC Bank, National Association [Member]        
Line of Credit Facility [Line Items]        
Amounts outstanding   56.7   0.0
Amount borrowed   $ 56.8 $ 57.2  
Number of days borrowed   88 days 88 days  
Weighted-average interest rate   2.53% 1.67%  
Weighted-average amount borrowed   $ 56.0 $ 55.8  
Standby Letters of Credit [Member]        
Line of Credit Facility [Line Items]        
Maximum borrowing capacity   61.8   56.8
Amounts outstanding   $ 0.0 $ 0.0 $ 0.0
Minimum [Member] | Standby Letters of Credit [Member]        
Line of Credit Facility [Line Items]        
Expiration Date   Nov. 01, 2018    
Maximum [Member] | Standby Letters of Credit [Member]        
Line of Credit Facility [Line Items]        
Expiration Date   Jul. 01, 2020