XML 60 R49.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-based Compensation Expense (Additional Information) (Details)
$ in Millions
3 Months Ended
Apr. 30, 2018
USD ($)
period
shares
Apr. 30, 2017
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense $ 54.4 $ 66.8
Acceleration of eligible stock awards   3.2
Market capitalization 2,000.0  
Restricted Stock Units (RSUs) and Performance Shares    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Awards vested in period, fair value $ 96.2 76.9
Awards granted in period (shares) | shares 391,900  
Restricted Stock Units (RSUs)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Awards granted in period (shares) | shares 200,000  
Allocated share-based compensation expense $ 41.7 50.0
Performance Stock Unit    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Awards granted in period (shares) | shares 200,000  
Allocated share-based compensation expense $ 6.5 10.9
Acceleration of eligible stock awards   $ 4.6
Award vesting period 3 years  
Employee Qualified Stock Purchase Plan 1998 ESP Plan    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Employee stock purchase plan maximum percentage of compensation to purchase shares by eligible participants 15.00%  
Employee stock purchase plan minimum percentage of common stock fair value defined to purchase shares by eligible participants 85.00%  
Employee stock purchase plan, number of exercise periods | period 4  
Employee stock purchase plan, term of exercise period 6 months  
Employee stock purchase plan, term of offering period 24 months  
Share-based Compensation Award, Tranche One | Performance Stock Unit    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
PSU annual vesting percentage 33.33%  
Share-based Compensation Award, Tranche Two | Performance Stock Unit    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
PSU annual vesting percentage 33.33%  
Share-based Compensation Award, Tranche Three | Performance Stock Unit    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
PSU annual vesting percentage 33.33%