Intangible Assets (Components Of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Gross Carrying Amount, Goodwill	$ 1,336	$ 1,221
Gross Carrying Amount, Trademarks	736	687
Gross Carrying Amount, Amortized Intangible Assets	854	807
Accumulated Amortization, Amortized Intangible Assets	495	464
Net Carrying Amount, Amortized Intangible Assets	359	343
Franchise Agreements [Member]
Goodwill [Roll Forward]
Gross Carrying Amount, Amortized Intangible Assets	643	594
Accumulated Amortization, Amortized Intangible Assets	417	401
Net Carrying Amount, Amortized Intangible Assets	$ 226	193
Finite-Lived Intangible Assets, Useful Life	32 years
Management Agreement [Member]
Goodwill [Roll Forward]
Gross Carrying Amount, Amortized Intangible Assets	$ 143	156
Accumulated Amortization, Amortized Intangible Assets	56	45
Net Carrying Amount, Amortized Intangible Assets	$ 87	111
Finite-Lived Intangible Assets, Useful Life	15 years
Trademarks [Member]
Goodwill [Roll Forward]
Gross Carrying Amount, Amortized Intangible Assets	$ 17	17
Accumulated Amortization, Amortized Intangible Assets	6	5
Net Carrying Amount, Amortized Intangible Assets	$ 11	12
Finite-Lived Intangible Assets, Useful Life	14 years
Other Intangible Assets [Member]
Goodwill [Roll Forward]
Gross Carrying Amount, Amortized Intangible Assets	$ 51	40
Accumulated Amortization, Amortized Intangible Assets	16	13
Net Carrying Amount, Amortized Intangible Assets	$ 35	27
Customer Lists And Business Contracts [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	12 years
Minimum [Member] | Franchise Agreements [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	20 years
Minimum [Member] | Management Agreement [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	10 years
Minimum [Member] | Trademarks [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	3 years
Minimum [Member] | Customer Lists And Business Contracts [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	3 years
Maximum [Member] | Franchise Agreements [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	40 years
Maximum [Member] | Management Agreement [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	20 years
Maximum [Member] | Trademarks [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	20 years
Maximum [Member] | Customer Lists And Business Contracts [Member]
Goodwill [Roll Forward]
Finite-Lived Intangible Assets, Useful Life	15 years
Trademarks [Member]
Goodwill [Roll Forward]
Gross Carrying Amount, Trademarks	$ 725	675
Continuing Operations [Member]
Goodwill [Roll Forward]
Gross Carrying Amount, Goodwill	$ 1,336	$ 1,221