Detail of Accrued Expenses and Other Current Liabilities Detail of Accrued Expenses - Additional Information (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Detail of Accrued Expenses [Abstract]
Total Rewards liability	$ 47	$ 50
Self-insurance accruals	$ 204us-gaap_SelfInsuranceReserveCurrent	$ 208us-gaap_SelfInsuranceReserveCurrent

Value of deferred revenue or cost to provide products or services, which is expected to be recognized in income or incurred within one year or the normal operating cycle, if longer, resulting from customer loyalty program. Excludes liability associated with frequent flier programs. Includes liability associated with customer loyalty programs for other businesses, for example, but is not limited to, hotels, supermarkets, credit card companies, automobile rental companies, and book sellers.

No definition available.

Name:	us-gaap_CustomerLoyaltyProgramLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant