INVESTMENTS - Carrying Value of Non-marketable Equity Securities Measured Using the Measurement Alternative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Equity Securities without Readily Determinable Fair Value, Annual Amount [Abstract]
Measurement alternative—carrying value	$ 771,000,000		$ 771,000,000		$ 700,000,000
Measurement alternative—impairment losses	50,000,000	$ 3,000,000	53,000,000	$ 8,000,000
Measurement alternative—downward changes for observable prices	19,000,000	12,000,000	19,000,000	12,000,000
Measurement alternative—upward changes for observable prices	17,000,000	19,000,000	42,000,000	$ 85,000,000
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Cumulative Amount [Abstract]
Measurement alternative—impairment losses	65,000,000		65,000,000
Measurement alternative—downward changes for observable prices	52,000,000		52,000,000
Measurement alternative—upward changes for observable prices	384,000,000		$ 384,000,000
Non-marketable equity securities, impairment loss recognized in earnings	$ 0	$ 0