ACCOUNTS RECEIVABLE AND OTHER FINANCIAL ASSETS - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from customers	$ 973		$ 510
Receivables from marketing affiliates	29		32
Provision charged to earnings	11	$ 241
Revenue
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision charged to earnings	6	$ 58
Prepaid expenses, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Prepayments to customers	82		107
Other assets, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Prepayments to customers	$ 37		$ 45