XML 67 R52.htm IDEA: XBRL DOCUMENT v3.10.0.1
FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS - Convertible Senior Notes (Details) - USD ($)
Jul. 31, 2018
Jan. 31, 2018
Jul. 31, 2017
Reported Value Measurement | Fair Value, Measurements, Nonrecurring      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Debt Instrument, Fair Value Disclosure $ 429,598,000   $ 0
Estimate of Fair Value Measurement | Fair Value, Measurements, Nonrecurring      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Debt Instrument, Fair Value Disclosure 685,527,000   $ 0
Convertible Debt      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Debt Instrument, Interest Rate, Stated Percentage   0.00%  
Debt Instrument, Unamortized Discount (137,719,000)    
Unamortized Debt Issuance Expense $ (7,683,000)