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Stock and Stock-Based Incentive Plans Stock And Stock-Based Incentive Plans (Assumptions Used to Estimate Option Values) (Details)
3 Months Ended
May 31, 2018
May 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate 0.00% 0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum 29.00% 29.40%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum 31.40% 32.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate 29.10% 29.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum 1.70% 0.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum 2.90% 2.10%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 4 years 7 months 6 days 4 years 7 months 6 days