Equity, Reclassification Out of Accumulated Other Comprehensive Income (Loss) (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
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Net actuarial loss	$ 15		$ 9	$ 29		$ 17
Prior service credit	(9)		(6)	(15)		(10)
Total before tax	741		1,282	1,733		945
Tax benefit	(276)		(452)	(616)		(547)
Net income	465		830	1,117		398
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Net income	(9)			(12)
Defined Benefit Plans Items [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Net actuarial loss	(15)	[1]		(29)	[1]
Prior service credit	9	[1]		15	[1]
Total before tax	(6)			(14)
Tax benefit	2			5
Net income	(4)			(9)
Gains (Losses) on Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Total before tax	(8)			(5)
Tax benefit	3			2
Net income	(5)			(3)
Gains (Losses) on Cash Flow Hedges [Member] | Commodity Contract [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss)
Cost of sales	$ (8)			$ (5)

[1] (a) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost, as further discussed in Note 8. Net periodic benefit cost is reflected in operating expenses and general and administrative expenses.