VARIABLE INTEREST ENTITIES - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Variable Interest Entity [Line Items]
Carrying amount	[1]	$ 12,483		$ 12,483		$ 17,370
Eliminations
Variable Interest Entity [Line Items]
Carrying amount		(6,233)		(6,233)		(7,696)
VIEs which are not primary beneficiary
Variable Interest Entity [Line Items]
Carrying amount		78		78		71
Loss from equity method investments		7	$ 13	$ 29	$ 38
Consolidated VIEs
Variable Interest Entity [Line Items]
Variable interest entities outsourcing agreement initial term				5 years
Carrying amount		237		$ 237		228
Consolidated VIEs | Eliminations
Variable Interest Entity [Line Items]
Liabilities associated with the certain outsourcing agreements and purchase options		$ 130		$ 130		$ 127

[1] Our consolidated total assets as of September 30, 2020 and December 31, 2019 include total assets of variable interest entities (VIEs) of $237 million and $228 million, respectively, which can only be used to settle the obligations of the VIEs. Our consolidated total liabilities as of September 30, 2020 and December 31, 2019 include total liabilities of VIEs of $53 million and $27 million, respectively, for which the creditors of the VIEs have no recourse to us. See Note 8. Variable Interest Entities.