CONTINGENCIES AND COMMITMENTS (Details)	1 Months Ended	3 Months Ended				9 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) vacation_ownership_unit	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) vacation_ownership_unit	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 Property
Commitments and Contingencies Disclosure [Line Items]
Commitments to subsidize associations		$ 2,000,000				$ 2,000,000
Finance leases, future minimum payments due		14,000,000				14,000,000
Surety bonds issued		104,000,000				104,000,000
Vacation ownership projects currently under development		9,000,000				9,000,000
Time share, accrued costs		(4,000,000)				(4,000,000)
Estimate of possible loss	$ 10,000,000
Recovery of funds								$ 6,000,000
Gain on litigation		(3,000,000)			$ (17,000,000)	(5,000,000)	$ (33,000,000)
Settled Litigation
Commitments and Contingencies Disclosure [Line Items]
Proceeds from legal settlements			$ 3,000,000
Gain on litigation						3,000,000
Revolving corporate credit facility, net
Commitments and Contingencies Disclosure [Line Items]
Letters of credit outstanding		3,000,000				3,000,000
Letter of Credit
Commitments and Contingencies Disclosure [Line Items]
Letters of credit outstanding		4,000,000				4,000,000
Revolving corporate credit facility, net | Corporate Credit Facility
Commitments and Contingencies Disclosure [Line Items]
Credit facility		600,000,000				600,000,000
New York City, New York
Commitments and Contingencies Disclosure [Line Items]
Purchase commitment		182,000,000				182,000,000
Purchase commitment obligation due, 2020		120,000,000				120,000,000
Purchase commitment obligation due, 2021		62,000,000				62,000,000
Bali Indonesia Resort Two
Commitments and Contingencies Disclosure [Line Items]
Purchase commitment obligation due, 2019		3,000,000				3,000,000
Purchase commitment obligation due, 2020		23,000,000				23,000,000
Purchase commitment obligation due, 2021		$ 2,000,000				$ 2,000,000
Number of vacation ownership units expected to be acquired | vacation_ownership_unit		88				88
San Francisco, California
Commitments and Contingencies Disclosure [Line Items]
Purchase commitment		$ 101,000,000				$ 101,000,000
Purchase commitment obligation due, 2020		55,000,000				55,000,000
Purchase commitment obligation due, 2021		46,000,000				46,000,000
Facility And Other Operating Leases | New York City, New York
Commitments and Contingencies Disclosure [Line Items]
Finance leases, future minimum payments due		7,000,000				7,000,000
Information technology hardware and software
Commitments and Contingencies Disclosure [Line Items]
Purchase commitment		67,000,000				67,000,000
Purchase commitment obligation due, 2019		13,000,000				13,000,000
Purchase commitment obligation due, 2020		26,000,000				26,000,000
Purchase commitment obligation due, 2021		15,000,000				15,000,000
Purchase commitment obligation due, 2022		8,000,000				8,000,000
Purchase commitment obligation due, 2023		5,000,000				5,000,000
Hurricane
Commitments and Contingencies Disclosure [Line Items]
Number of other resorts and lodging properties (more than) | Property										20
Gains, property damage									$ 1,000,000
Gain on business interruption insurance recovery				$ 9,000,000				32,000,000
Business interruption insurance recovery, deductible								$ 3,000,000
Exchange & Third-Party Management
Commitments and Contingencies Disclosure [Line Items]
Guarantor obligations, maximum exposure		33,000,000				33,000,000
Guarantor obligations, maximum exposure. due remainder of fiscal year		4,000,000				4,000,000
Guarantor obligations, maximum exposure, due in second year		10,000,000				10,000,000
Guarantor obligations, maximum exposure, due in third year		9,000,000				9,000,000
Guarantor obligations, maximum exposure, due in fourth year		4,000,000				4,000,000
Guarantor obligations, maximum exposure, due in five year		2,000,000				2,000,000
Guarantor obligations, maximum exposure, due after fifth year		4,000,000				4,000,000
Other Guarantees
Commitments and Contingencies Disclosure [Line Items]
Guarantor obligations, maximum exposure		$ 3,000,000				$ 3,000,000