Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended					6 Months Ended
	Jun. 30, 2012		Mar. 31, 2012	Jun. 30, 2011		Jun. 30, 2012		Jun. 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 loss (gain)	(18)			(9)		(19)		(9)
Amortization of net prior service credit	25	[1]		23	[1]	52	[1]	54	[1]
Contributions [Abstract]
Contribution of common stock to a benefit plan						130	[2]
Pension Benefits [Member]
Components of Net Periodic Benefit Costs:
Service cost	46			46		97		94
Interest cost	113			121		228		239
Expected return on plan assets	(128)			(130)		(257)		(257)
Recognized net actuarial loss	26			19		53		36
Amortization of prior service credit	(5)			(6)		(11)		(12)
Recognized settlement loss	14			20		30		50
Defined benefit plans	66			70		140		150
Defined contribution plans	15			16		31		32
Net Periodic Benefit Plan Cost	81			86		171		182
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income:
Net actuarial loss (gain)	(18)			(9)		(19)		(9)
Amortization of net prior service credit	5			6		11		12
Amortization of net actuarial losses	(40)			(39)		(83)		(86)
Total Recognized in Other Comprehensive Income	(53)	[3]		(42)	[3]	(91)	[3]	(83)	[3]
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income	28			44		80		99
Contributions [Abstract]
Contributions by employer						237
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	148					148
Anticipated total cash contributions to defined benefit and post retirement plans in the current year	385					385
Anticipated total contributions to defined benefit plans in current year	515					515
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	2			2		4		4
Interest cost	11			12		22		24
Expected return on plan assets	0			0		0		0
Recognized net actuarial loss	1			0		1		0
Amortization of prior service credit	(11)			(10)		(21)		(20)
Recognized settlement loss	0			0		0		0
Defined benefit plans	3			4		6		8
Defined contribution plans	0			0
Net Periodic Benefit Plan Cost	3			4		6		8
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income:
Net actuarial loss (gain)	0			0		0		0
Amortization of net prior service credit	11			10		21		20
Amortization of net actuarial losses	(1)			0		(1)		0
Total Recognized in Other Comprehensive Income	10	[3]		10	[3]	20	[3]	20	[3]
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income	13			14		26		28
Contributions [Abstract]
Contributions by employer						33
Anticipated additional contributions to the defined benefit and post retirement plans in current fiscal year	47					47
Anticipated total cash contributions to defined benefit and post retirement plans in the current year	$ 80					$ 80

[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.