STOCK-BASED COMPENSATION - Summary of Activity for Stock Options (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Balance, beginning of period (in shares)	15,122
Granted (in shares)	163,494
Exercised (in shares)	(13,217)
Forefeited, (in shares)	(12,653)
Balance, end of period (in shares)	152,746	15,122
Exercisable, (in shares)	1,954
Weighted-average Exercise Price
Balance, beginning of period (in dollars per share)	$ 484
Granted (in dollars per share)	1,411
Exercised (in dollars per share)	466
Forfeited (in dollars per share)	1,411
Balance, end of period (in dollars per share)	1,401	$ 484
Exercisable (in dollars per share)	$ 660
Aggregate Intrinsic Value (in millions)
Balance	$ 126	$ 24
Exercisable	$ 3
Weighted-average Remaining Contractual Term (in years)
Balance	9 years 3 months 18 days	2 years 7 months 6 days
Exercisable	2 years 1 month 6 days