Segment Information (Reconciliation of Net Income to Adjusted EBITDA) (Details) - USD ($) $ in Millions	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net (loss)/income	$ (7)	$ 27	$ (174)	$ 22	$ 64	$ 45	$ 26	$ 21		$ (132)	$ 157	$ 162
Provision for income taxes	(2)	15	(48)	9	14	21	10	5		(26)	50	61
Depreciation and amortization	(24)	(24)	(25)	(25)	(28)	(26)	(27)	(29)		(98)	(109)	(99)
Interest expense, net	30	29	28	25	25	25	26	24		112	100	60
Stock-based compensation	(5)	(5)	(5)	(4)	(4)	(4)	(4)	(3)		(21)	(20)
Separation-related	1	0	0	1	0	0	1	21		2	22	77
Transaction-related item					0	20	0	0	$ 20	0	20
Transaction-related, net	0	0	(5)	(8)	(10)	(12)	(11)	(7)		(12)	(40)	(36)
Foreign currency impact of highly inflationary countries	0	1	0	0	1	3	0	1		2	5	3
Impairments, net	0	0	206	0	0	0	45	0		206	45	0
Contract termination					(1)	34	9	0		0	42	0
Restructuring	5	0	16	13	8	0	0	0		34	8	0
Adjusted EBITDA	$ 56	$ 101	$ 63	$ 107	$ 153	$ 190	$ 159	$ 111		327	613	507
Nonseparation related [Member] | Wyndham Hotels & Resorts, Inc. 2018 Equity and Incentive Plan
Segment Reporting Information [Line Items]
Stock-based compensation										$ (19)	$ (15)	$ (9)