SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of the Components of Income from Leveraged Leases (Details) - Domestic and international leveraged leases - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leveraged Lease [Line Items]
Pretax leveraged lease income	$ 11	$ 25	$ 25
Net impact of Tax Reform Legislation	0	0	48
Income tax expense	0	(6)	(9)
Net leveraged lease income	$ 11	$ 19	$ 64