REVENUE - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Leases and related maintenance and rental revenues	$ 3,704,045	$ 3,784,744	$ 3,512,867
Contracted not recognized revenue	2,700,000
Initial direct costs of leases	89,000	105,000
Sales commissions expense	44,000	43,000	37,000
Maintenance Services
Disaggregation of Revenue [Line Items]
Leases and related maintenance and rental revenues	$ 965,000	$ 950,000	$ 909,000