Intangible Assets - Definite-Lived Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets
Definite-Lived Intangible Assets, Gross Carrying Amount	$ 976	$ 976
Accumulated Amortization	(811)	(793)
Marketing agreements
Finite-Lived Intangible Assets
Definite-Lived Intangible Assets, Gross Carrying Amount	730	730
Accumulated Amortization	(658)	(648)
Contracts
Finite-Lived Intangible Assets
Definite-Lived Intangible Assets, Gross Carrying Amount	193	193
Accumulated Amortization	(100)	(92)
Other
Finite-Lived Intangible Assets
Definite-Lived Intangible Assets, Gross Carrying Amount	53	53
Accumulated Amortization	$ (53)	$ (53)