Segment Information (Summary of Net Revenues and Adjusted EBITDA by Segment) (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]
Net Revenues	$ 337	$ 560	$ 1,004	$ 1,561
Adjusted EBITDA	101	190	271	461
Reportable Segments
Segment Reporting Information [Line Items]
Net Revenues	337	559	1,004	1,557
Adjusted EBITDA	119	208	322	515
Reportable Segments | Hotel Franchising
Segment Reporting Information [Line Items]
Net Revenues	236	379	661	979
Adjusted EBITDA	117	195	308	470
Reportable Segments | Hotel Management
Segment Reporting Information [Line Items]
Net Revenues	101	180	343	578
Adjusted EBITDA	2	13	14	45
Corporate and Other
Segment Reporting Information [Line Items]
Net Revenues	0	1	0	4
Adjusted EBITDA	$ (18)	$ (18)	$ (51)	$ (54)