Fair Value Measurements - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2021	Feb. 28, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value Measurements [Line Items]
Proceeds from warrant exercises			$ 183,007	$ 2,500	$ 0
Warrants outstanding (in shares)			0
Series E-2 Preferred Shares | Traton
Fair Value Measurements [Line Items]
Warrants to purchase preferred stock (in shares)		4,331,644
Exercise price per share (in dollars per share)		$ 11.31
Proceeds from warrant exercises		$ 49,000
Series E Convertible Preferred Stock | Navistar, Inc.
Fair Value Measurements [Line Items]
Warrants to purchase preferred stock (in shares)	9,477,073
Exercise price per share (in dollars per share)	$ 14.14
Proceeds from warrant exercises	$ 134,000