BASIS OF PRESENTATION - Restructuring (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue from contracts with customers	$ 585	$ 994	$ 1,933	$ 2,934
Restructuring	(20)	0	(20)	0
Workforce Reduction Plan
Segment Reporting Information [Line Items]
Restructuring	(20)
Cost reimbursements
Segment Reporting Information [Line Items]
Revenue from contracts with customers	255	280	767	819
Cost reimbursements	(255)	(280)	(767)	(819)
Cost reimbursements | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Revenue from contracts with customers	7
Cost reimbursements	(7)
Vacation Ownership
Segment Reporting Information [Line Items]
Revenue from contracts with customers	507	869	1,680	2,563
Exchange & Third-Party Management
Segment Reporting Information [Line Items]
Revenue from contracts with customers	71	110	234	348
Operating segments | Vacation Ownership | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Restructuring	(11)
Operating segments | Vacation Ownership | Cost reimbursements | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Revenue from contracts with customers	5
Cost reimbursements	(5)
Operating segments | Exchange & Third-Party Management | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Restructuring	(3)
Operating segments | Exchange & Third-Party Management | Cost reimbursements | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Revenue from contracts with customers	2
Cost reimbursements	(2)
Corporate and Other
Segment Reporting Information [Line Items]
Revenue from contracts with customers	7	$ 15	$ 19	$ 23
Corporate and Other | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Restructuring	(6)
Corporate and Other | Cost reimbursements | Workforce Reduction Plan
Segment Reporting Information [Line Items]
Revenue from contracts with customers	0
Cost reimbursements	$ 0