Restructuring (Narrative) (Details) $ in Millions		3 Months Ended	12 Months Ended
		Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)		Dec. 31, 2019 USD ($) employee		Dec. 31, 2018 USD ($) employee	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring			$ 39		$ 9		$ 16
Cash payments			20		14		9
Restructuring related obligations			26	[1]	7	[1]	12	$ 5
COVID-19 (Member)
Restructuring Cost and Reserve [Line Items]
Restructuring related obligations	[2]		6		0
Vacation Ownership | COVID-19 (Member) | Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Operating Lease, Impairment Loss			5
Travel and Membership | COVID-19 (Member) | Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Operating Lease, Impairment Loss		$ 24	24
Facility-Related
Restructuring Cost and Reserve [Line Items]
Restructuring			24				0
Cash payments			1				1
Restructuring related obligations			23		0		0	1
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			12
Cash payments			10
Restructuring related obligations			2		0
Personnel-Related
Restructuring Cost and Reserve [Line Items]
Restructuring			3		9		16
Cash payments			9		14		8
Restructuring related obligations			1		7		12	$ 4
Restructuring Plan 2020
Restructuring Cost and Reserve [Line Items]
Restructuring			37
Restructuring related obligations			25
Restructuring Plan 2020 | COVID-19 (Member) | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			36
Restructuring Plan 2020 | Vacation Ownership | COVID-19 (Member) | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			14
Restructuring Plan 2020 | Travel and Membership | COVID-19 (Member) | Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Operating Lease, Impairment Loss		24
Restructuring Plan 2020 | Travel and Membership | COVID-19 (Member) | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			22
Restructuring Plan 2020 | Corporate and Other | COVID-19 (Member) | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			0
Restructuring Plan 2020 | Facility-Related
Restructuring Cost and Reserve [Line Items]
Cash payments			12
Restructuring Plan 2020 | Facility-Related | COVID-19 (Member) | Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			2
Restructuring Plan 2020 | Facility-Related | Vacation Ownership | COVID-19 (Member)
Restructuring Cost and Reserve [Line Items]
Restructuring			1
Restructuring Plan 2020 | Facility-Related | Travel and Membership | COVID-19 (Member)
Restructuring Cost and Reserve [Line Items]
Restructuring		$ 22
Restructuring Plan 2020 | Facility-Related | Corporate and Other | COVID-19 (Member)
Restructuring Cost and Reserve [Line Items]
Restructuring			1
Restructuring Plan 2020 | Other Restructuring [Member] | Vacation Ownership | COVID-19 (Member)
Restructuring Cost and Reserve [Line Items]
Restructuring			12
Restructuring Plan 2020 | Personnel-Related | Travel and Membership
Restructuring Cost and Reserve [Line Items]
Restructuring			1
Restructuring Plan 2019
Restructuring Cost and Reserve [Line Items]
Restructuring					$ 5
Number of positions eliminated | employee					100
Restructuring Plan 2019 | Personnel-Related
Restructuring Cost and Reserve [Line Items]
Cash payments			5		$ 1
Restructuring related obligations			1
Restructuring Plan 2019 | Personnel-Related | Vacation Ownership
Restructuring Cost and Reserve [Line Items]
Restructuring					2
Restructuring Plan 2019 | Personnel-Related | Travel and Membership
Restructuring Cost and Reserve [Line Items]
Restructuring			1		2
Restructuring Plan 2019 | Personnel-Related | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Restructuring			1		1
Restructuring Plan 2018
Restructuring Cost and Reserve [Line Items]
Restructuring							$ 16
Number of positions eliminated | employee							500
Restructuring Plan 2018 | Personnel-Related
Restructuring Cost and Reserve [Line Items]
Cash payments			3		13		$ 4
Restructuring related obligations			$ 1
Restructuring Plan 2018 | Personnel-Related | Vacation Ownership
Restructuring Cost and Reserve [Line Items]
Restructuring					3		11
Restructuring Plan 2018 | Personnel-Related | Travel and Membership
Restructuring Cost and Reserve [Line Items]
Restructuring							4
Restructuring Plan 2018 | Personnel-Related | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Restructuring					$ 1		$ 1

[1] See Note 28—Restructuring for details.

[2] See Note 26—COVID-19 Related Items for details.