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Business and Summary of Significant Accounting Policies - Assumption Used to Estimate the Fair Value of Stock-Based Awards (Details)
12 Months Ended
Jan. 31, 2016
Jan. 31, 2015
Jan. 31, 2014
Performance Stock Unit      
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Range of expected volatilities 27.00% 30.00% 34.00%
Expected dividends 0.00% 0.00% 0.00%
Range of risk-free interest rates 0.20% 0.10% 0.10%
Employee Qualified Stock Purchase Plan 1998 ESP Plan      
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Expected dividends 0.00% 0.00% 0.00%
Employee Qualified Stock Purchase Plan 1998 ESP Plan | Minimum      
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Range of expected volatilities 28.00% 29.00% 27.00%
Range of expected lives 6 months 6 months 6 months
Range of risk-free interest rates 0.10% 0.00% 0.10%
Employee Qualified Stock Purchase Plan 1998 ESP Plan | Maximum      
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Range of expected volatilities 29.00% 33.00% 36.00%
Range of expected lives 2 years 2 years 2 years
Range of risk-free interest rates 0.70% 0.60% 0.40%