Convertible Debt - Schedule of Outstanding Principal Amount and Carrying Value of Notes (Details) - USD ($) |
Jun. 30, 2020 |
Dec. 31, 2019 |
Aug. 19, 2019 |
Nov. 30, 2018 |
Nov. 19, 2018 |
Sep. 15, 2017 |
---|---|---|---|---|---|---|
Debt Instrument [Line Items] | ||||||
Net carrying amount | $ 1,988,213,000 | $ 1,456,195,000 | ||||
Convertible Debt | 2017 Notes | ||||||
Debt Instrument [Line Items] | ||||||
Principal | 431,250,000 | 431,250,000 | $ 431,250,000 | |||
Unamortized debt discount | (49,329,000) | (59,830,000) | ||||
Net carrying amount | 381,921,000 | 371,420,000 | ||||
Convertible Debt | 2018 Notes | ||||||
Debt Instrument [Line Items] | ||||||
Principal | 575,000,000 | 575,000,000 | $ 575,000,000.0 | $ 500,000,000.0 | ||
Unamortized debt discount | (147,371,000) | (161,275,000) | ||||
Net carrying amount | 427,629,000 | 413,725,000 | ||||
Convertible Debt | 2019 Notes | ||||||
Debt Instrument [Line Items] | ||||||
Principal | 948,750,000 | 948,750,000 | $ 948,750,000 | |||
Unamortized debt discount | (260,306,000) | (277,700,000) | ||||
Net carrying amount | 688,444,000 | $ 671,050,000 | ||||
Convertible Debt | 2020 Accreting Notes | ||||||
Debt Instrument [Line Items] | ||||||
Principal | 535,000,000 | |||||
Unamortized debt discount | (44,781,000) | |||||
Net carrying amount | $ 490,219,000 |