Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Cash and cash equivalents		$ 540,308		$ 540,308		$ 262,728
Long-term common stock warrant liabilities		12,318		12,318		178,232
Change in fair value of common stock warrant liabilities	[1]	(113,601)	$ 0	(81,898)	$ 0
Private Warrant
Class of Stock [Line Items]
Long-term common stock warrant liabilities		12,300		12,300		$ 53,700
Change in fair value of common stock warrant liabilities		$ (48,400)		$ (41,400)

[1] Retroactively restated for the reverse recapitalization as described in Notes 1 and 3.