INVESTMENTS - Carrying Value of Non-marketable Equity Securities Measured Using the Measurement Alternative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Equity Securities without Readily Determinable Fair Value, Annual Amount [Abstract]
Measurement alternative—carrying value	$ 865,000,000		$ 865,000,000		$ 700,000,000
Measurement alternative—impairment losses	2,000,000	$ 1,000,000	55,000,000	$ 9,000,000
Measurement alternative—downward changes for observable prices	0	4,000,000	19,000,000	16,000,000
Measurement alternative—upward changes for observable prices	40,000,000	23,000,000	82,000,000	$ 108,000,000
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Cumulative Amount [Abstract]
Measurement alternative—impairment losses	67,000,000		67,000,000
Measurement alternative—downward changes for observable prices	52,000,000		52,000,000
Measurement alternative—upward changes for observable prices	424,000,000		$ 424,000,000
Non-marketable equity securities, impairment loss recognized in earnings	$ 0	$ 0