RESTRICTED CASH - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 2,326	$ 495	$ 787
Restricted cash included in other assets	$ 120		$ 53
Restricted Cash and Cash Equivalents, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other assets		Other assets
Total cash, cash equivalents and restricted cash	$ 2,446	$ 495	$ 840	$ 139