Debt - Conversion Value of Convertible Notes (Details) - Senior Notes - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended |
---|---|---|
Mar. 31, 2020 |
Dec. 31, 2019 |
|
Debt Instrument [Line Items] | ||
Total by which the notes’ if-converted value exceeds their principal amount | $ 1,285.0 | $ 858.6 |
Senior convertible notes due 2022 | ||
Debt Instrument [Line Items] | ||
Total by which the notes’ if-converted value exceeds their principal amount | 686.9 | 486.2 |
Senior convertible notes due 2023 | ||
Debt Instrument [Line Items] | ||
Total by which the notes’ if-converted value exceeds their principal amount | $ 598.1 | $ 372.4 |