ACCOUNTS RECEIVABLE AND OTHER FINANCIAL ASSETS - Summary of the Activity of the Allowance for Expected Credit Losses on Prepayments to Customers (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Contract With Customer, Asset, Prepayments To Customers, Allowance for Credit Loss [Abstract]
Balance, beginning of year	$ 55	$ 6
Provision charged to expense	1	50
Write-offs and adjustments	(2)	0
Balance, end of period	$ 54	$ 56