SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 19,000		$ 12,900
Revenue	13,211	$ 15,665
Transferred over Time
Disaggregation of Revenue [Line Items]
Revenue	1,600	1,100
Aircraft sales
Disaggregation of Revenue [Line Items]
Revenue	0	5,710
Charter flight revenue
Disaggregation of Revenue [Line Items]
Revenue	11,516	6,684
Aircraft Management revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 1,695	$ 3,271