CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Class A Common Stock Class A	Class A Common Stock Class B Convertible	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Loss	(Accumulated Deficit) Retained Earnings
Beginning Balance at Dec. 31, 2020	$ 446,192	$ 16	$ 2	$ 655,241	$ (782,104)	$ (3,885)	$ 576,922
Beginning Balance (in shares) at Dec. 31, 2020		16,307	1,964		(8,684)
Net loss	(110,020)	$ 0	$ 0	0	$ 0	0	(110,020)
Other comprehensive income (loss)	(1,836)	0	0	0	0	(1,836)	0
Issuance of class A common stock upon exercise of stock options	23,854	$ 0	0	23,854	0	0	0
Issuance of class A common stock upon exercise of stock options (in shares)		159
Share-based compensation expense	6,848	$ 0	0	6,848	0	0	0
Ending Balance at Mar. 31, 2021	365,038	$ 16	$ 2	685,943	$ (782,104)	(5,721)	466,902
Ending Balance (in shares) at Mar. 31, 2021		16,466	1,964		(8,684)
Net loss	(299,347)	$ 0	$ 0	0	$ 0	0	(299,347)
Other comprehensive income (loss)	397	0	0	0	0	397	0
Issuance of class A common stock upon exercise of stock options	244	$ 0	0	244	0	0	0
Issuance of class A common stock upon exercise of stock options (in shares)		2
Share-based compensation expense	11,087	$ 0	0	11,087	0	0	0
Ending Balance at Jun. 30, 2021	77,419	$ 16	$ 2	697,274	$ (782,104)	(5,324)	167,555
Ending Balance (in shares) at Jun. 30, 2021		16,468	1,964		(8,684)
Net loss	(36,136)	$ 0	$ 0	0	$ 0	0	(36,136)
Other comprehensive income (loss)	(1,457)	0	0	0	0	(1,457)	0
Issuance of class A common stock upon exercise of stock options	7,282	$ 0	0	7,282	0	0	0
Issuance of class A common stock upon exercise of stock options (in shares)		50
Issuance of class A common stock under employee stock purchase plan	2,854	$ 0	$ 0	2,854	$ 0	0	0
Issuance of class A common stock under employee stock purchase plan, (in shares)		5	0		0
Issuance of class A common stock under public offerings, net of issuance costs	399,469	$ 1	$ 0	399,468	$ 0	0	0
Issuance of class A common stock under public offerings, net of issuance costs, (in shares)		555	0		0
Share-based compensation expense	11,883	$ 0	$ 0	11,883	$ 0	0	0
Ending Balance at Sep. 30, 2021	461,314	$ 17	$ 2	1,118,761	$ (782,104)	(6,781)	131,419
Ending Balance (in shares) at Sep. 30, 2021		17,078	1,964		(8,684)
Net loss	(89,977)	$ 0	$ 0	0	$ 0	0	(89,977)
Other comprehensive income (loss)	(762)	0	0	0	0	(762)	0
Issuance of class A common stock upon exercise of stock options	9,271	$ 0	0	9,271	0	0	0
Issuance of class A common stock upon exercise of stock options (in shares)		58
Issuance of class A common stock upon vesting of restricted stock units, net of withholding taxes	(4,754)	$ 0	$ 0	(4,754)	$ 0	0	0
Issuance of class A common stock upon vesting of restricted stock units, net of withholding taxes, (in shares)		11	0		0
Issuance of class A common stock under public offerings, net of issuance costs	590,994	$ 1	$ 0	590,993	$ 0	0	0
Issuance of class A common stock under public offerings, net of issuance costs, (in shares)		859	0		0
Share-based compensation expense	12,872	$ 0	$ 0	12,872	$ 0	0	0
Ending Balance at Dec. 31, 2021	978,958	$ 18	$ 2	1,727,143	$ (782,104)	(7,543)	41,442
Ending Balance (in shares) at Dec. 31, 2021		18,006	1,964		(8,684)
Net loss	(130,751)	$ 0	$ 0	0	$ 0	0	(130,751)
Other comprehensive income (loss)	(2,009)	0	0	0	0	(2,009)	0
Issuance of class A common stock upon exercise of stock options	288	$ 0	0	288	0	0	0
Issuance of class A common stock upon exercise of stock options (in shares)		2
Issuance of class A common stock under employee stock purchase plan	2,805	$ 0	$ 0	2,805	$ 0	0	0
Issuance of class A common stock under employee stock purchase plan, (in shares)		7	0		0
Issuance of class A common stock upon vesting of restricted stock units, net of withholding taxes	(501)	$ 0	$ 0	(501)	$ 0	0	0
Issuance of class A common stock upon vesting of restricted stock units, net of withholding taxes, (in shares)		3	0		0
Share-based compensation expense	14,209	$ 0	$ 0	14,209	$ 0	0	0
Ending Balance at Mar. 31, 2022	$ 862,999	$ 18	$ 2	$ 1,743,944	$ (782,104)	$ (9,552)	$ (89,309)
Ending Balance (in shares) at Mar. 31, 2022		18,018	1,964		(8,684)