Debt - Summary of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Instrument [Line Items]
Amortization of debt discount			$ 5,685	$ 6,000
Senior Notes | 2023 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	$ 1,581	$ 1,581	3,162	3,162
Amortization of debt discount	2,380	2,255	4,728	4,480
Total	$ 3,961	$ 3,836	$ 7,890	$ 7,642
Effective interest rate (as a percent)	5.45%		5.45%