FAIR VALUE MEASUREMENTS - Narrative (Details) $ in Millions	Mar. 31, 2020 USD ($) Years	Dec. 31, 2016 USD ($)
Didi Chuxing | Long-term Investments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in equity securities without readily determinable FV	$ 400
Grab | Long-term Investments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 180
Trip.com Group 1.25% Notes due 2022 | Long-term Investments | Trip.com Group convertible debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost of Trip.com Group convertible notes		$ 25
Weighted Average Cost of Capital | Grab and Didi Chuxing [Member] | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (percentages)	12.00%
Weighted Average Cost of Capital | Grab and Didi Chuxing [Member] | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (percentages)	14.00%
EBITDA Multiple | Grab and Didi Chuxing [Member] | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (number)	13
EBITDA Multiple | Grab and Didi Chuxing [Member] | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (number)	15
Volatility | Grab and Didi Chuxing [Member] | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (percentages)	60.00%
Volatility | Grab and Didi Chuxing [Member] | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (percentages)	70.00%
Expected Term | Grab and Didi Chuxing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, inputs (number) | Years	4
Valuation, Market Approach [Member] | Grab
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs, valuation approach allocation	25.00%
Valuation, Income Approach [Member] | Grab
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs, valuation approach allocation	75.00%