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, 2020	Dec. 31, 2019	Dec. 31, 2018
Leveraged Lease [Line Items]
Pretax leveraged lease income (loss)	$ (180)	$ 11	$ 25
Income tax benefit (expense)	98	0	(6)
Net leveraged lease income (loss)	$ (82)	$ 11	$ 19