Summary of Significant Accounting Policies - Liquidity Matters (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended
	Jul. 31, 2021	Apr. 30, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Policies
Net (loss) income			$ (138,595)	$ (63,853)
Accumulated deficit			1,533,431		$ 1,394,836
Cash, cash equivalents and restricted cash			158,526	$ 65,289	84,614	$ 48,855
Marketable securities			593,660		829,896
Short-term Credit Line, outstanding balance			$ 50,055		$ 50,052
Common stock, shares issued			96,259,000		95,140,000
Convertible Notes
Policies
Outstanding principal balance		$ 287,500	$ 287,500
Per annum interest rate (as a percent)		2.25%	2.25%
Net proceeds		$ 278,300
Equity offering
Policies
Common stock, shares issued	5,175,000
Stock issued (in dollars per share)	$ 113
Payment of offering expenses	$ 400
Proceeds from issuance of common stock	$ 551,200