Leasing (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) distribution_center	Sep. 30, 2014 USD ($)
Operating Leased Assets [Line Items]
Number of distribution centers leased | distribution_center			10
Schedule of Rent Expense [Abstract]
Minimum rentals	$ 576	$ 569	$ 1,721	$ 1,692
Contingent rentals	9	9	25	26
Rent Expense	585	578	1,746	1,718
Less: sublease income	(5)	(5)	(16)	(16)
Rent expense, net	$ 580	$ 573	1,730	1,702
Proceeds from sale-leaseback transactions			$ 34	$ 328
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