FAIR VALUE MEASUREMENTS - Schedule of Fair Value Measurements on a Nonrecurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lessor operating lease assets	$ 761	$ 791
Lessor operating lease assets		92
Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired collateral-dependent loans	312	338
MSRs	193	243
Lessor operating lease assets		92
Level 1 | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired collateral-dependent loans	0	0
MSRs	0	0
Lessor operating lease assets		0
Level 2 | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired collateral-dependent loans	312	338
MSRs	0	0
Lessor operating lease assets		92
Level 3 | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired collateral-dependent loans	0	0
MSRs	193	243
Lessor operating lease assets		$ 0
Leased assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lessor operating lease assets	57
Leased assets | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lessor operating lease assets	57
Leased assets | Level 1 | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lessor operating lease assets	0
Leased assets | Level 2 | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lessor operating lease assets	57
Leased assets | Level 3 | Nonrecurring measurement basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lessor operating lease assets	$ 0