Employee Benefit Plans (Details) (USD $) In Millions	6 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
Jun. 30, 2010	Jul. 31, 2011 Employer Contributions to Pension Plans [Member]	Sep. 30, 2011 Employer Contributions to Pension Plans [Member]	Jun. 30, 2011 Pension Plans, Defined Benefit [Member]	Jun. 30, 2010 Pension Plans, Defined Benefit [Member]	Jun. 30, 2011 Pension Plans, Defined Benefit [Member]	Jun. 30, 2010 Pension Plans, Defined Benefit [Member]	Jun. 30, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]	Jun. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Jun. 30, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]	Jun. 30, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of net periodic benefit cost:
Service cost				$ 22	$ 21	$ 45	$ 43	$ 2	$ 2	$ 5	$ 5
Interest cost				22	21	43	41	5	7	11	13
Expected return on plan assets				(28)	(28)	(56)	(56)	0	0	0	0
Amortization of:
Prior service cost (credit)				0	0	1	1	(5)	(5)	(11)	(10)
Net loss				3	1	6	1	1	1	1	2
Net periodic benefit cost				19	15	39	30	3	5	6	10
Employee Benefit Plans (Textual)
Contributions to pension plans	$ 53	$ 25	$ 75

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The amount of gains or losses recognized in net periodic benefit cost.

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The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

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The increase in the fair value of plan assets from contributions made by the employer.

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An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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Employee Benefit Plans.

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