FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Foreign currency exchange contracts | Not Designated as Hedging Instrument
Liabilities:
Derivatives	$ 11	$ 8
Cross-currency swaps | Net Investment Hedging | Designated as Hedging Instrument
Liabilities:
Derivatives	35	70
Recurring basis
Assets:
Cash equivalents	148	41
Restricted cash	1,214	1,211
Liabilities:
Acquisition-related contingent consideration	313	328
Recurring basis | Foreign currency exchange contracts | Not Designated as Hedging Instrument
Assets:
Derivative Assets	0	3
Liabilities:
Derivatives	11	11
Recurring basis | Cross-currency swaps | Net Investment Hedging | Designated as Hedging Instrument
Liabilities:
Derivatives	35	70
Recurring basis | Level 1
Assets:
Cash equivalents	107	8
Restricted cash	1,214	1,211
Liabilities:
Acquisition-related contingent consideration	0	0
Recurring basis | Level 1 | Foreign currency exchange contracts | Not Designated as Hedging Instrument
Assets:
Derivative Assets	0	0
Liabilities:
Derivatives	0	0
Recurring basis | Level 1 | Cross-currency swaps | Net Investment Hedging | Designated as Hedging Instrument
Liabilities:
Derivatives	0	0
Recurring basis | Level 2
Assets:
Cash equivalents	41	33
Restricted cash	0	0
Liabilities:
Acquisition-related contingent consideration	0	0
Recurring basis | Level 2 | Foreign currency exchange contracts | Not Designated as Hedging Instrument
Assets:
Derivative Assets	0	3
Liabilities:
Derivatives	11	11
Recurring basis | Level 2 | Cross-currency swaps | Net Investment Hedging | Designated as Hedging Instrument
Liabilities:
Derivatives	35	70
Recurring basis | Level 3
Assets:
Cash equivalents	0	0
Restricted cash	0	0
Liabilities:
Acquisition-related contingent consideration	313	328
Recurring basis | Level 3 | Foreign currency exchange contracts | Not Designated as Hedging Instrument
Assets:
Derivative Assets	0	0
Liabilities:
Derivatives	0	0
Recurring basis | Level 3 | Cross-currency swaps | Net Investment Hedging | Designated as Hedging Instrument
Liabilities:
Derivatives	$ 0	$ 0