Stockholders' Equity (Deficit) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stockholders' Equity
Proceeds from shares sold, net		$ 57,190	$ 564,859	$ 450,953
Common Stock
Stockholders' Equity
Issued (in shares)		521,911	2,578,967	29,035,137
Proceeds from shares sold, net		$ 5	$ 26	$ 290
At Market Issuance Sales Agreements | Common Stock
Stockholders' Equity
Issued (in shares)			2,600,000	29,100,000
Proceeds from shares sold, net			$ 565,000	$ 446,000
June 2021 Sales Agreement | Common Stock
Stockholders' Equity
Issued (in shares)	0
Proceeds from shares sold, net	$ 500,000