Convertible Senior Notes - Summary of Fair Value and Carrying Value of Convertible Senior Notes (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
0% Convertible Senior Notes Due 2026 | Fair Value
Debt Instrument [Line Items]
Convertible senior notes	$ 421,493
0% Convertible Senior Notes Due 2026 | Carrying Value
Debt Instrument [Line Items]
Convertible senior notes	272,764
0.125% Convertible Senior Notes Due 2024 | Fair Value
Debt Instrument [Line Items]
Convertible senior notes	670,050	$ 663,615
0.125% Convertible Senior Notes Due 2024 | Carrying Value
Debt Instrument [Line Items]
Convertible senior notes	383,133	369,032
1.50% Convertible Senior Notes Due 2022 | Fair Value
Debt Instrument [Line Items]
Convertible senior notes	1,356	265,488
1.50% Convertible Senior Notes Due 2022 | Carrying Value
Debt Instrument [Line Items]
Convertible senior notes	$ 286	$ 72,482