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Stock-Based Compensation (Additional Information) (Details 2) - USD ($)
$ in Millions
3 Months Ended
Nov. 30, 2017
Nov. 30, 2016
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Share repurchase program, remaining authorized repurchase amount $ 356.7  
Stock-based compensation recognized for modification 24.9  
2017 Share Repurchase Program [Member]    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Share repurchase program, amount authorized $ 450.0  
Shares repurchased 3,200,000  
Shares repurchased, value $ 93.2  
Restricted Stock Awards [Member]    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Awards vested 800,000  
Performance-based restricted stock units [Member]    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Restricted stock units awarded 400,000 600,000
Award vesting period 3 years  
Performance-based restricted stock units [Member] | Maximum    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Award vesting percentage 150.00%  
Time-based restricted stock units [Member]    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Restricted stock units awarded 1,300,000 1,000,000
Award vesting period 3 years  
Market based restricted stock units [Member]    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Restricted stock units awarded 400,000 400,000
Award vesting percentage 200.00%  
Award vesting period 3 years  
Plan 2011    
Schedule of Weighted Average Assumptions for Fair Values of Stock Options[Line Items]    
Shares available for issuance under share based compensation plan 12,327,622