Retirement Benefits (Details 6) (Pension Plans [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans [Member]
Components of net periodic
Service cost	$ 184	$ 172	$ 146
Interest cost	389	391	387
Expected return on plan assets	(607)	(552)	(541)
Recognized net loss	21	10	7
Net amortization	32	33	35
Total change	19	54	34
Estimated pension benefit payments
2012	361
2013	380
2014	398
2015	418
2016	438
2017 to 2021	$ 2,488

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 aggregate benefits expected to be paid in the five fiscal years thereafter (the aggregate amount of benefits expected to be paid in years 6 through 10 after the date of the latest statement of financial position).

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The amount of the benefits expected to be paid in Year 5.

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The amount of the benefits expected to be paid in Year 4.

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The amount of the benefits expected to be paid in Year 1.

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The amount of the benefits expected to be paid in Year 3.

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The amount of the benefits expected to be paid in Year 2.

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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 aggregate amount of net gain (loss) recognized in net periodic benefit cost due to settlements and curtailments. Curtailments result from an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services. Settlements result from an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts to cover vested benefits.

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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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