Quarterly report pursuant to Section 13 or 15(d)

Long-term Debt - Summary of Components of Notes (Details)

v3.20.2
Long-term Debt - Summary of Components of Notes (Details) - USD ($)
Jun. 30, 2020
Dec. 31, 2019
Sep. 30, 2019
Senior Unsecured Notes      
Debt Instrument [Line Items]      
Principal $ 900,000,000 $ 500,000,000  
Accrued interest 17,000,000 13,000,000  
Unamortized premium 6,000,000 7,000,000  
Less: Unamortized financing costs (12,000,000) (8,000,000)  
Carrying value of convertible notes 911,000,000 512,000,000  
Senior Unsecured Notes | 2024 Notes      
Debt Instrument [Line Items]      
Principal 500,000,000   $ 150,000,000
Convertible Senior Notes | 4.125% Convertible Senior Notes Due September 1, 2022      
Debt Instrument [Line Items]      
Principal 150,000,000 150,000,000  
Accrued interest 2,000,000 2,000,000  
Less: Unamortized financing costs (2,000,000) (3,000,000)  
Carrying value of convertible notes $ 150,000,000 $ 149,000,000