Other Postretirement Benefits (Net Periodic Postretirement Benefit Costs) (Details) (Other Postretirement Benefits [Member], USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Mar. 31, 2011
Other Postretirement Benefits [Member]
Service cost	$ 6	$ 6	$ 12	$ 12
Interest cost on accumulated other postretirement benefit obligation	21	23	42	46
Expected return on plan assets	(22)	(22)	(44)	(44)
Amortization of net actuarial loss	22	23	44	46
Amortization of prior service cost	(2)	(3)	(4)	(6)
Amortization of transition obligation	1	1	2	2
NET PERIODIC POSTRETIREMENT BENEFIT COST	26	28	52	56
Cost capitalized	(9)	(10)	(18)	(20)
Cost deferred	4	1	9
Cost charged to operating expenses	21	19	43	36
Expected contributions					$ 84

Defined Benefit Plan Cost Capitalized

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Defined Benefit Plan Cost Charged To Operating Expenses

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Defined Benefit Plan Cost Deferred

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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 amount of the transition obligation or asset recognized in net periodic benefit cost.

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The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

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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.

+ References

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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.

+ References

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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.

+ References

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