VARIABLE INTEREST ENTITIES - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Variable Interest Entity [Line Items]
Assets	[1]	$ 12,780		$ 12,780		$ 13,382
Loss from equity method investments				(60)	$ 4
Eliminations
Variable Interest Entity [Line Items]
Assets		(6,185)		$ (6,185)		(6,387)
Consolidated VIEs
Variable Interest Entity [Line Items]
Variable interest entities outsourcing agreement initial term				5 years
Assets		219		$ 219		233
Consolidated VIEs | Eliminations
Variable Interest Entity [Line Items]
Liabilities associated with the certain outsourcing agreements and purchase options		125		125		131
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets		89		89		$ 75
Loss from equity method investments		$ (7)	$ (10)	$ (12)	$ (22)

[1] Our consolidated total assets as of June 30, 2021 and December 31, 2020 include total assets of variable interest entities (VIEs) of $219 million and $233 million, respectively, which can only be used to settle the obligations of the VIEs. Our consolidated total liabilities as of June 30, 2021 and December 31, 2020 include total liabilities of VIEs of $56 million and $60 million, respectively, for which the creditors of the VIEs have no recourse to us. See Note 9. Variable Interest Entities.