Retirement Benefits (Details 3) (Pension Plans [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans [Member]
Changes in projected benefit obligations and the fair value of plan assets
Benefit obligation at beginning of year	$ 7,223	$ 6,758
Service cost	184	172	146
Interest cost	389	391	387
Benefits paid	324	296
Actuarial loss (gain)	607	198
Balance at end of year	8,079	7,223	6,758
Fair value of plan assets at beginning of year	6,834	5,627
Actual return (loss) on plan assets	256	859
Employer contributions	34	644
Fair value of plan assets at end of year	6,800	6,834	5,627
Accrued liability	$ 1,279	$ 389

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

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The net increase or decrease of changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

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1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

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

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The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

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