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Debt - Convertible Senior Notes, Notes Hedges, Warrants Narrative (Details)
3 Months Ended 6 Months Ended 9 Months Ended 12 Months Ended
Oct. 31, 2021
USD ($)
$ / shares
shares
Oct. 31, 2020
USD ($)
Jul. 31, 2020
USD ($)
Jan. 31, 2021
shares
Oct. 31, 2021
USD ($)
trading_day
$ / shares
shares
Oct. 31, 2020
USD ($)
Jan. 31, 2021
shares
Feb. 01, 2021
Sep. 30, 2017
USD ($)
Jun. 30, 2013
USD ($)
Debt Instrument [Line Items]                    
Payments on convertible senior notes | $ $ 9,000 $ 0     $ 80,000 $ 249,946,000        
Number of trading days related to warrants (in days) | trading_day         60          
2020 Notes                    
Debt Instrument [Line Items]                    
Convertible senior notes, principal amount | $                   $ 250,000,000
Class A | 2020 Notes                    
Debt Instrument [Line Items]                    
Warrants settled (shares)       1,600,000            
Class of warrant outstanding (in shares) 0       0          
Class A | 2022 Notes                    
Debt Instrument [Line Items]                    
Convertible senior notes, principal amount | $ $ 1,000       $ 1,000          
Debt instrument, convertible, number of shares         6.7982          
Warrants expires in 2020                    
Debt Instrument [Line Items]                    
Shares covered by each purchased options or warrants (in shares) 3,100,000       3,100,000          
Number of trading days related to warrants (in days) | trading_day         60          
Exercise price of warrants (in dollars per share) | $ / shares $ 107.96       $ 107.96          
Warrants expires In 2023                    
Debt Instrument [Line Items]                    
Shares covered by each purchased options or warrants (in shares) 7,800,000       7,800,000          
Number of trading days related to warrants (in days) | trading_day         60          
Exercise price of warrants (in dollars per share) | $ / shares $ 213.96       $ 213.96          
Convertible Debt | 2020 Notes                    
Debt Instrument [Line Items]                    
Contractual interest rate                   1.50%
Payments on convertible senior notes | $     $ 250,000,000              
Convertible Debt | 2022 Notes                    
Debt Instrument [Line Items]                    
Contractual interest rate               0.25% 0.25%  
Convertible senior notes, principal amount | $                 $ 1,150,000,000  
Repurchase of notes percentage         100.00%          
Carrying amount of the equity component | $                 $ 223,000,000  
Effective interest rate of liability component 0.55%       0.55%       4.60%  
Liability issuance costs | $                 $ 14,000,000  
Equity issuance costs | $                 $ 4,000,000  
Convertible Debt | Class A | 2020 Notes                    
Debt Instrument [Line Items]                    
Debt conversion, converted instrument, shares issued             1,700,000      
Initial conversion price (in dollars per share) | $ / shares $ 81.74       $ 81.74          
Indexed shares (in shares) 3,100,000       3,100,000          
Purchase of treasury stock from the exercise of convertible senior notes hedges (in shares)         1,700,000          
Convertible Debt | Class A | 2022 Notes                    
Debt Instrument [Line Items]                    
Initial conversion price (in dollars per share) | $ / shares $ 147.10       $ 147.10          
Indexed shares (in shares) 7,800,000       7,800,000          
Convertible Debt | Debt Conversion, Option One | Convertible Senior Notes                    
Debt Instrument [Line Items]                    
Threshold trading days (in trading days) | trading_day         20          
Threshold consecutive trading days | trading_day         30          
Threshold percentage of conversion price         130.00%          
Convertible Debt | Debt Conversion, Option Two | Convertible Senior Notes                    
Debt Instrument [Line Items]                    
Threshold trading days (in trading days) | trading_day         5          
Threshold consecutive trading days | trading_day         5          
Convertible Debt | Debt Conversion, Option Two | Convertible Senior Notes | Maximum                    
Debt Instrument [Line Items]                    
Threshold percentage of stock trading price         98.00%