Summary of Significant Accounting Policies - Liquidity Matters (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Jul. 31, 2021	Sep. 30, 2020	Apr. 30, 2020	Oct. 31, 2019	Apr. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Apr. 26, 2019	Dec. 31, 2018
Policies
Net (loss) income						$ (471,716)	$ (229,743)	$ (124,827)
Accumulated deficit						1,394,836	929,318
Cash, cash equivalents and restricted cash						84,614	48,855	$ 61,981		$ 51,004
Marketable securities						829,896	688,606
Short-term Credit Line, outstanding balance						$ 50,052	$ 50,054
Common stock, shares issued	5,175,000	4,791,665		5,714,286	5,263,158	95,140,000	86,223,000
Stock issued (in dollars per share)	$ 113			$ 35	$ 19
Payment of offering expenses	$ 400	$ 300		$ 400	$ 600
Proceeds from issuance of common stock	$ 551,200	$ 271,000		$ 216,200	$ 108,100
Net proceeds							$ 278,316
Loss on debt extinguishment							$ 5,848
Convertible Notes
Policies
Outstanding principal balance			$ 287,500			$ 287,500
Per annum interest rate (as a percent)			2.25%			2.25%
Equity offering
Policies
Common stock, shares issued	5,175,000	4,791,665		6,571,428	6,052,631
Stock issued (in dollars per share)	$ 113	$ 60.00		$ 35	$ 19
Payment of offering expenses	$ 400	$ 300		$ 400	$ 600
Proceeds from issuance of common stock	$ 551,200	$ 271,000		$ 216,200	$ 108,100
Option for additional shares
Policies
Common stock, shares issued				857,142					789,473