Quarterly report pursuant to Section 13 or 15(d)

Convertible Senior Notes (Details)

v3.20.1
Convertible Senior Notes (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2017
USD ($)
Debt Instrument, Redemption [Line Items]      
Proceeds from convertible senior notes     $ 282,200
Convertible senior notes conversion ratio 0.0631793 0.0631793  
Convertible senior notes $ 285,238 $ 284,954  
Convertible Debt [Member]      
Debt Instrument, Redemption [Line Items]      
Aggregate principal amount $ 287,500    
Convertible senior notes interest rate per annum 6.25%