REVENUE - Revenue with Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	$ 1,010	$ 702	$ 3,001	$ 1,797
Cost reimbursements		234	819	652
Financing	72	48	209	119
Total Revenues	1,082	750	3,210	1,916
Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	896	661	2,643	1,756
Cost reimbursements		232	835	650
Financing	71	48	206	119
Total Revenues	967	709	2,849	1,875
Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	111	40	348	40
Cost reimbursements		8	68	8
Financing	1	0	3	0
Total Revenues	112	40	351	40
Sale of vacation ownership products
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	350	252	1,001	632
Sale of vacation ownership products | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	350	252	1,001	632
Sale of vacation ownership products | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	0	0	0	0
Ancillary revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	63	42	188	106
Ancillary revenues | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	62	42	185	106
Ancillary revenues | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	1	0	3	0
Management fee revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	44	35	138	85
Management fee revenues | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	35	28	110	78
Management fee revenues | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	12	8	38	8
Other services revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	124	49	383	83
Other services revenues | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	28	21	89	55
Other services revenues | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	62	20	191	20
Management and exchange
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	231	126	709	274
Management and exchange | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	125	91	384	239
Management and exchange | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	75	28	232	28
Rental
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	149	90	472	239
Rental | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	135	86	423	235
Rental | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	14	4	48	4
Cost reimbursements
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	280	234	819	652
Cost reimbursements	280
Cost reimbursements | Vacation Ownership
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost reimbursements	286
Cost reimbursements | Exchange & Third-Party Management
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost reimbursements	22
Corporate and other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	3	1	10	1
Cost reimbursements		(6)	(84)	(6)
Financing	0	0	0	0
Total Revenues	3	1	10	1
Corporate and other | Sale of vacation ownership products
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	0	0	0	0
Corporate and other | Ancillary revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	0	0	0	0
Corporate and other | Management fee revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	(3)	(1)	(10)	(1)
Corporate and other | Other services revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	34	8	103	8
Corporate and other | Management and exchange
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	31	7	93	7
Corporate and other | Rental
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contracts with customers	0	$ 0	$ 1	$ 0
Corporate and other | Cost reimbursements
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost reimbursements	$ (28)