Quarterly report pursuant to Section 13 or 15(d)

Property and Equipment, Net of Accumulated Depreciation (Narrative) (Details)

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Property and Equipment, Net of Accumulated Depreciation (Narrative) (Details)
$ in Millions
 1 Months Ended 3 Months Ended 6 Months Ended
Sep. 30, 2017
Aug. 31, 2017
USD ($)
ft²
item
Nov. 30, 2017
USD ($)
Nov. 30, 2016
USD ($)
Nov. 30, 2017
USD ($)
Nov. 30, 2016
USD ($)
Property, Plant and Equipment [Line Items]            
Depreciation expense     $ 28.4 $ 25.5 $ 56.5 $ 50.8
Cost of building purchased         $ 95.5 $ 46.8
Multi-Building Campus [Member] | County Of Monroe Industrial Development Agency [Member]            
Property, Plant and Equipment [Line Items]            
Public benefits and inducements expiration date Dec. 31, 2039          
Multi-Building Campus [Member] | Rochester, NY [Member]            
Property, Plant and Equipment [Line Items]            
Number of buildings planned to be purchased | item   5        
Renovation square feet | ft²   300,000        
Estimated cost of buildings to be purchased and building renovations   $ 60.0        
Cost of building purchased     34.7      
Escrow for building renovations     $ 16.0