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 9 Months Ended
Sep. 30, 2017
Aug. 31, 2017
USD ($)
ft²
item
Feb. 28, 2018
USD ($)
Nov. 30, 2017
USD ($)
Feb. 28, 2017
USD ($)
Feb. 28, 2018
USD ($)
Feb. 28, 2017
USD ($)
Property, Plant and Equipment [Line Items]              
Depreciation expense     $ 31.5   $ 26.4 $ 88.0 $ 77.2
Cost of building purchased           122.0 $ 66.8
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      
Construction in progress     $ 31.5     $ 31.5