ACCOUNTS RECEIVABLE AND OTHER FINANCIAL ASSETS (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from customers	$ 883		$ 1,200
Receivables from marketing affiliates	28		110
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of year	49	$ 51
Provision charged to earnings	206	53
Write-offs and adjustments	(59)	(55)
Currency translation adjustments	12	(2)
Balance, end of period	208	47
Prepaid expenses, allowance for credit loss	54		6
Merchant revenues
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision charged to earnings	32
Sales and other expenses
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Expected credit loss expenses	223	$ 53
Sales and other expenses | Prepayments to customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Expected credit loss expenses	49
Prepaid expenses and other current assets, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Prepayments to certain customers	118		$ 232
Other assets, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Prepayments to certain customers	$ 56