XML 66 R46.htm IDEA: XBRL DOCUMENT v3.21.1
Fair Value Measurements - Convertible Senior Notes (Details) - Convertible Debt - USD ($)
$ in Thousands
Jan. 31, 2021
Jan. 31, 2020
Sep. 30, 2018
Convertible Senior Notes Due 2023      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Unpaid principal $ 115,000 $ 575,000  
Debt interest rate percentage     0.50%
Convertible Senior Notes Due 2023 | Fair Value, Inputs, Level 2      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Convertible debt, fair value disclosures 373,928 743,504  
Convertible Senior Notes Due 2024      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Unpaid principal $ 690,000 0  
Debt interest rate percentage 0.00%    
Convertible Senior Notes Due 2024 | Fair Value, Inputs, Level 2      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Convertible debt, fair value disclosures $ 725,100 $ 0