Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended					9 Months Ended
	Sep. 30, 2012		Mar. 31, 2012	Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Components of Net Periodic Benefit Costs:
Defined contribution plans						$ 0		$ 0
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income:
Net actuarial gain	31			14		50		23
Amortization of net prior service credit	35	[1]		13	[1]	87	[1]	67	[1]
Contributions [Abstract]
Contribution of common stock to a benefit plan						130	[2]	130
Pension Benefits [Member]
Components of Net Periodic Benefit Costs:
Service cost	49			46		146		140
Interest cost	113			121		341		360
Expected return on plan assets	(129)			(129)		(386)		(386)
Recognized net actuarial loss	26			17		79		53
Amortization of prior service credit	(6)			(5)		(17)		(17)
Recognized settlement loss	25			11		55		61
Defined benefit plans	78			61		218		211
Defined contribution plans	17			17		48		49
Net Periodic Benefit Plan Cost	95			78		266		260
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income:
Net actuarial gain	0			0		(19)		(9)
Amortization of net prior service credit	6			5		17		17
Amortization of net actuarial losses	(51)			(28)		(134)		(114)
Total Recognized in Other Comprehensive Income	(45)	[3]		(23)	[3]	(136)	[3]	(106)	[3]
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income	50			55		130		154
Contributions [Abstract]
Contributions by employer						310
Stock Issued During Period, Shares, Employee Benefit Plan			15.4
Contribution of common stock to a benefit plan			130
Anticipated additional contributions to the defined benefit and post retirement plans in current fiscal year	40					40
Anticipated total cash contributions to defined benefit and post retirement plans in the current year	350					350
Anticipated total contributions to defined benefit plans in current year	480					480
Previously Disclosed Anticipated Total Contributions, Cash and Stock, In Current Year To Defined Benefit Pension Plans	560					560
Retiree Health [Member]
Components of Net Periodic Benefit Costs:
Service cost	3			2		7		6
Interest cost	9			11		31		35
Expected return on plan assets	0			0		0		0
Recognized net actuarial loss	0			0		1		0
Amortization of prior service credit	(10)			(10)		(31)		(30)
Recognized settlement loss	0			0		0		0
Defined benefit plans	2			3		8		11
Defined contribution plans	0			0
Net Periodic Benefit Plan Cost	2			3		8		11
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income:
Net actuarial gain	(31)			(14)		(31)		(14)
Amortization of net prior service credit	10			10		31		30
Amortization of net actuarial losses	0			0		(1)		0
Total Recognized in Other Comprehensive Income	(21)	[3]		(4)	[3]	(1)	[3]	16	[3]
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income	(19)			(1)		7		27
Contributions [Abstract]
Contributions by employer						64
Anticipated additional contributions to the defined benefit and post retirement plans in current fiscal year	18					18
Anticipated total cash contributions to defined benefit and post retirement plans in the current year	$ 82					$ 82

[1] (2) Reclassified to Total Net Periodic Benefit Cost - refer to Note 12 - Employee Benefit Plans for additional information.

[2] (4)Refer to Note 12 - Employee Benefit Plans for additional information.

[3] (1)Amounts represent the pre-tax effect included within Other comprehensive income. Refer to Note 14 - Comprehensive Income for related tax effects and the after-tax amounts.