SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) obligation	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Revenue, Major Customer [Line Items]
Number of performance obligations | obligation	2
Basic vehicle warranty term	4 years
Revenues	$ 172,740	$ 149,432
Electric Vehicle Purchase Agreement | Customer Concentration Risk | Accounts Receivable | Government of Saudi Arabia
Revenue, Major Customer [Line Items]
Concentration risk (as a percent)	66.90%		68.50%
Vehicle Sales with RVG
Revenue, Major Customer [Line Items]
Revenues	$ 89,500	$ 18,700
Vehicle Sales with OTA and Remarketing
Revenue, Major Customer [Line Items]
Vehicle Sales primarily with OTA and Remarketing	33,400		$ 28,700
Vehicle Sales with OTA and Remarketing | Other Current Liabilities
Revenue, Major Customer [Line Items]
Vehicle Sales primarily with OTA and Remarketing	9,000		7,700
Vehicle Sales with OTA and Remarketing | Other Noncurrent Liabilities
Revenue, Major Customer [Line Items]
Vehicle Sales primarily with OTA and Remarketing	$ 24,400		$ 21,000