Transactions with Former Parent and Former Subsidiaries (Narrative) (Details) $ in Millions	3 Months Ended															12 Months Ended
	Dec. 31, 2020 USD ($)		Sep. 30, 2020 USD ($)		Jun. 30, 2020 USD ($)	[1]	Mar. 31, 2020 USD ($)	[1]	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	[2]	Jun. 30, 2019 USD ($)		Mar. 31, 2019 USD ($)	[2]	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 09, 2019 USD ($)
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Accrued expenses and other liabilities	$ 67								$ 72							$ 67	$ 72
Cash paid to Wyndham Hotels related to Awaze																0	69	$ 476
Escrow deposit	29								37							29	37
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	(2)	[1]	$ 0	[1]	$ 0		$ 0		$ 12	$ 0		$ 6	[2]	$ (1)		(2)	18	456
British Travel Association and Regulatory Authorities
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee	46															46
Accrued expenses and other liabilities	$ 22															$ 22
Change in proceeds																	27
Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Responsible liability for separation agreement																37.50%
Contingent and other corporate liabilities retained	0.25															0.25
Removal of capital lease obligation																		66
Removal of capital lease asset																		43
Related party expense																$ 1	1
Separation and Distribution Agreement, Portion of Certain Contingent and Other Corporate Liabilities Assumed	0.67															0.67
Separation and Distribution Agreement, Portion of Proceeds From Contingent and Other Corporate Assets	0.67															0.67
Post-closing Credit Support, Portion of Escrow Received Upon Release	0.67															0.67
Post-closing Credit Support, Portion of Guarantees Assumed	0.67															0.67
Affiliated Entity | Cendant | Accrued Liabilities and Other Liabilities
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Liabilities assumed																$ 13	13
Tax liabilities assumed																12
Other contingent and corporate liabilities assumed																$ 1
Affiliated Entity | Realogy
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Responsible liability for separation agreement																62.50%
Affiliated Entity | Wyndham Hotels And Resorts, Inc.
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Contingent and other corporate liabilities retained	0.33															0.33
Separation and Distribution Agreement, Portion of Certain Contingent and Other Corporate Liabilities Assumed	0.33															0.33
Separation and Distribution Agreement, Portion of Proceeds From Contingent and Other Corporate Assets	0.33															0.33
Post-closing Credit Support, Portion of Escrow Received Upon Release	0.33															0.33
Wyndham Hotels And Resorts, Inc.
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Receivable from related party	$ 7															$ 7
Cash paid to Wyndham Hotels related to Awaze																	40
Transaction Service Agreement | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Related party expense																		8
Revenue from related parties																		6
Tradename Royalty Buy-Out
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Payment for tradename royalty buy-out																	5
Sale Of European Vacation Rental Business
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax																	6
Sale Of European Vacation Rental Business | European vacation rentals business [Member] | Accrued Liabilities and Other Liabilities
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Accrued expenses and other liabilities	90															90
Sale Of European Vacation Rental Business | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Escrow deposit																			$ 5
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax																(2)
Sale Of European Vacation Rental Business | Affiliated Entity | Financial Guarantee
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee												$ 180
Sale Of European Vacation Rental Business | Affiliated Entity | Financial Guarantee | Awaze [Member]
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee	44															44
Sale Of European Vacation Rental Business | Affiliated Entity | Indemnification Agreement
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Accrued expenses and other liabilities	40															40
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Other Assets
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Receivable from related party	21															21
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Financial Guarantee | British Travel Association and Regulatory Authorities
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee	81															81
Accrued expenses and other liabilities	39															39
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Financial Guarantee | British Travel Association and Regulatory Authorities | United Kingdom, Pounds
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee			58
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Financial Guarantee | British Travel Association and Regulatory Authorities | United States of America, Dollars
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee	79															79
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Indemnification Agreement | Other Assets
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Receivable from related party	13															13
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Letter of Credit [Member] | British Travel Association and Regulatory Authorities | United Kingdom, Pounds
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee			$ 36
Sale Of European Vacation Rental Business | Wyndham Hotels And Resorts, Inc. | Letter of Credit [Member] | British Travel Association and Regulatory Authorities | United States of America, Dollars
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Secured bonding facility and perpetual guarantee	48															48
Sale Of North American Vacation Rental Business | Affiliated Entity | Indemnification Agreement
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Business Combination, Indemnification Assets, Amount as of Acquisition Date	$ 2															2
General and Administrative Expense [Member] | Transaction Service Agreement | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Related party expense																1	3
General and Administrative Expense [Member] | Sale Of European Vacation Rental Business | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Related party expense																1	2	3
General and Administrative Expense [Member] | Sale Of North American Vacation Rental Business | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Related party expense																1	3
Separation and Related Costs [Member] | Transaction Service Agreement | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Related party expense																	2
Other | Transaction Service Agreement | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Revenue from related parties																	1
Other | Sale Of North American Vacation Rental Business | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Revenue from related parties																2	3
Net Revenue [Member] | Sale Of European Vacation Rental Business | Affiliated Entity
Separation Adjustments And Transactions With Former Parent And Subsidiaries [Line Items]
Revenue from related parties																$ 1	$ 2	$ 3

[1] The results of operations for 2020 include impacts related to COVID-19. See Note 26—COVID-19 Related Items for additional details.

[2] The Company sold its North American vacation rentals business on October 22, 2019. This business did not meet the criteria to be classified as a discontinued operation; therefore, its results of operations are reflected within continuing operations through the date of sale.