Summary of Significant Accounting Policies Income Statement Impact of Accounting Policy Change (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Change in Accounting Principle [Line Items]
Cost of goods sold	$ 6,057	$ 5,844	$ 12,250	$ 11,779
Income from continuing operations before income taxes	1,365	1,496	3,139	3,297
Provision for income taxes on continuing operations	335	397	722	789
Income from continuing operations after income taxes	1,030	1,099	2,417	2,508
Income from discontinued operations after income taxes	4	76	1,972	171
Net income	1,034	1,175	4,389	2,679
As Reported [Member]
Change in Accounting Principle [Line Items]
Cost of goods sold	6,057	5,844	12,250	11,779
Income from continuing operations before income taxes	1,365	1,496	3,139	3,297
Provision for income taxes on continuing operations	335	397	722	789
Income from continuing operations after income taxes	1,030	1,099	2,417	2,508
Income from discontinued operations after income taxes	4	76	1,972	171
Net income	1,034	1,175	4,389	2,679
As reported under LIFO [Member]
Change in Accounting Principle [Line Items]
Cost of goods sold	6,067	5,830	12,271	11,771
Income from continuing operations before income taxes	1,355	1,510	3,118	3,305
Provision for income taxes on continuing operations	332	400	716	792
Income from continuing operations after income taxes	1,023	1,110	2,402	2,513
Income from discontinued operations after income taxes	4	78	1,972	175
Net income	1,027	1,188	4,374	2,688
Impact of change in accounting principle [Member]
Change in Accounting Principle [Line Items]
(Decrease) Increase to cost of goods sold	(10)	14	(21)	8
(Decrease) Increase to income from continuing operations before income taxes	10	(14)	21	(8)
(Decrease) Increase to provision for income taxes on continuing operations	3	(3)	6	(3)
(Decrease) Increase to income from continuing operations after income taxes	7	(11)	15	(5)
(Decrease) Increase to income from discontinued operations after taxes	0	(2)	0	(4)
(Decrease) Increase to net income	$ 7	$ (13)	$ 15	$ (9)