FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Net Investment Hedging | Currency Swap | Designated as Hedging Instrument
Liabilities:
Cross-currency swaps	$ 13
Recurring basis
Assets:
Cash equivalents	2,696	$ 197
Liabilities:
Acquisition-related contingent consideration	316	339
Recurring basis | Net Investment Hedging | Currency Swap | Designated as Hedging Instrument
Liabilities:
Cross-currency swaps	13	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents	2,646	166
Liabilities:
Acquisition-related contingent consideration	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Net Investment Hedging | Currency Swap | Designated as Hedging Instrument
Liabilities:
Cross-currency swaps	0	0
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents	50	31
Liabilities:
Acquisition-related contingent consideration	0	0
Recurring basis | Significant Other Observable Inputs (Level 2) | Net Investment Hedging | Currency Swap | Designated as Hedging Instrument
Liabilities:
Cross-currency swaps	13	0
Recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	0	0
Liabilities:
Acquisition-related contingent consideration	316	339
Recurring basis | Significant Unobservable Inputs (Level 3) | Net Investment Hedging | Currency Swap | Designated as Hedging Instrument
Liabilities:
Cross-currency swaps	$ 0	$ 0