BUSINESS SEGMENTS - Revenues (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	$ 649	$ 1,066	$ 2,139	$ 3,143
Vacation Ownership
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	571	940	1,884	2,769
Exchange & Third-Party Management
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	71	111	236	351
Operating segments
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	642	1,051	2,120	3,120
Operating segments | Vacation Ownership
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	571	940	1,884	2,769
Operating segments | Exchange & Third-Party Management
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	71	111	236	351
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	$ 7	$ 15	$ 19	$ 23