Leasing (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) distribution_center	Jun. 30, 2014 USD ($)
Operating Leased Assets [Line Items]
Number of distribution centers leased | distribution_center			10
Schedule of Rent Expense [Abstract]
Minimum rentals	$ 571	$ 565	$ 1,145	$ 1,122
Contingent rentals	8	8	16	17
Rent Expense	579	573	1,161	1,139
Less: sublease income	(5)	(5)	(11)	(10)
Rent expense, net	$ 574	$ 568	1,150	1,129
Proceeds from sale-leaseback transactions			$ 34	$ 5
Building [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract			15 years
Building [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract			25 years
Equipment [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract			3 years
Equipment [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract			10 years