Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Balance at Dec. 31, 2019	$ 698,426	$ (1,066)	$ 12	$ 1,012,218	$ 29	$ (313,833)	$ (1,066)
Balance, Shares at Dec. 31, 2019			119,897
Vesting of early exercised stock options	17			17
Issuance of common stock pursuant to equity incentive plans	2,743			2,743
Issuance of common stock pursuant to equity incentive plans, Shares			760
Stock-based compensation expense	$ 30,405			30,405
Accounting Standards Update [Extensible List]	Accounting Standards Update 2016-13
Net income (loss)	$ (54,612)					(54,612)
Balance at Mar. 31, 2020	675,913		$ 12	1,045,383	29	(369,511)
Balance, Shares at Mar. 31, 2020			120,657
Balance at Dec. 31, 2020	1,328,015		$ 13	1,660,379	29	(332,406)
Balance, Shares at Dec. 31, 2020			128,004
Vesting of early exercised stock options	4			4
Issuance of common stock pursuant to equity incentive plans	6,705			6,705
Issuance of common stock pursuant to equity incentive plans, Shares			1,663
Issuance of common stock in connection with at-the-market offering, net of issuance costs	989,615			989,615
Issuance of common stock pursuant in connection with at-the-market offerings, net of issuance costs, Shares			2,637
Stock-based compensation expense	40,677			40,677
Net income (loss)	76,296					76,296
Balance at Mar. 31, 2021	$ 2,441,312		$ 13	$ 2,697,380	$ 29	$ (256,110)
Balance, Shares at Mar. 31, 2021			132,304