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Income Taxes and Other Taxes (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Feb. 28, 2018
Feb. 28, 2017
Feb. 28, 2018
Feb. 28, 2017
Income Tax And Non Income Tax Disclosure [Abstract]        
Annualized effective income tax rate (percentage)     33.90%  
Effective income tax rate (percentage) 22.30%   23.80%  
Income tax expense due to remeasurement of deferred tax balances   $ 8.3   $ 0.0
Wisconsin | State Sales Tax Assessment [Member]        
Loss Contingencies [Line Items]        
Sales payable $ 5.4   $ 5.4