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FAIR VALUE MEASUREMENTS - Notional Amount of Foreign Currency Exchange Derivatives (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Losses on foreign currency exchange derivatives	$ 9	$ 23
Recurring Basis
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Assets at fair value	15,657		$ 14,054
Recurring Basis \| Level 2
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Assets at fair value	531		534
Foreign currency exchange derivatives \| Not Designated as Hedging Instrument \| Foreign currency purchases
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	653		898
Foreign currency exchange derivatives \| Not Designated as Hedging Instrument \| Foreign currency sales
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	863		839
Foreign currency exchange derivatives \| Not Designated as Hedging Instrument \| Recurring Basis
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Assets at fair value	7		9
Liabilities at fair value	11		7
Foreign currency exchange derivatives \| Not Designated as Hedging Instrument \| Recurring Basis \| Level 2
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Assets at fair value	7		9
Liabilities at fair value	$ 11		$ 7