ACCOUNTS RECEIVABLE AND OTHER FINANCIAL ASSETS - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from customers	$ 468		$ 510
Receivables from marketing affiliates	28		32
Provision charged to earnings	(12)	$ 199
Revenue
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision charged to earnings		$ 48
Prepaid expenses, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Prepayments to customers	95		107
Other assets, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Prepayments to customers	$ 38		$ 45