REVENUE - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Lease & related maintenance and rental revenues	$ 868,660	$ 933,833	$ 1,796,416	$ 1,833,392
Deferred revenue	613,972		613,972		$ 603,687
Amount of revenue recognized, previously included in deferred revenue			103,000
Increase in deferred revenue during the period			117,000
Contracted not recognized revenue	2,800,000		2,800,000
Capitalized sales commissions	94,000		94,000		105,000
Initial direct costs of leases			49,000		55,000
Amortization of capitalized sales commissions	11,000	11,000	22,000	22,000
Maintenance Services
Disaggregation of Revenue [Line Items]
Lease & related maintenance and rental revenues	238,000	$ 236,000	478,000	$ 475,000
ChoiceLease
Disaggregation of Revenue [Line Items]
Deferred revenue	$ 594,000		$ 594,000		$ 587,000