FAIR VALUE MEASUREMENTS - Financial Instruments and Related Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Financial Instruments and Fair Value [Line Items]
Cash and cash equivalents	$ 3,335	$ 2,934	$ 1,902	$ 1,838	$ 2,863	$ 2,858	$ 2,949
Other Assets
Financial Instruments and Fair Value [Line Items]
Other equity investments without readily determinable fair values	73			41
Fair Value, Inputs, Level 2
Financial Instruments and Fair Value [Line Items]
Cash and cash equivalents	3,300			1,800
Money market funds, at carrying value	$ 1,700			$ 169