VARIABLE INTEREST ENTITIES - Interest Income and Expense Recognized as a Result of Our Involvement with Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Variable Interest Entity [Line Items]
Interest income	$ 69	$ 45	$ 201	$ 113
Administrative expenses	68	$ 53	225	$ 114
Variable Interest Entity
Variable Interest Entity [Line Items]
Interest income	58		176
Interest expense to investors	12		41
Debt issuance cost amortization	2		5
Administrative expenses	0		1
Variable Interest Entity | Vacation Ownership Notes Receivable Securitizations
Variable Interest Entity [Line Items]
Interest income	57		164
Interest expense to investors	11		37
Debt issuance cost amortization	2		4
Administrative expenses	0		1
Variable Interest Entity | Warehouse Credit Facility
Variable Interest Entity [Line Items]
Interest income	1		12
Interest expense to investors	1		4
Debt issuance cost amortization	0		1
Administrative expenses	$ 0		$ 0