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Performance of extensive study based on projections of both assets and liabilities for determining optimal asset allocation for pension fund.

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Period at which the external investment managers typically send valuations to both the custodian and to the company after the quarter end.

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Period over which company has elected to amortize changes in market value of all plan assets.

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Voluntary contribution to pension plan.

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-Name Statement of Financial Accounting Standard (FAS)

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The interest rate used to adjust for the time value of money.

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Expected rate of compensation increases (for pay-related plans).

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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 employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. 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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Retirement Benefits (Details Textual) (USD $)	12 Months Ended
Retirement Benefits (Details Textual) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2007
Retirement Benefits (Textual) [Abstract]
Voluntary contribution to pension plan	$ 0
Discount rate on net periodic benefit costs				6.75%
Annual salary increase on net periodic benefit costs	3.84%	3.84%	4.18%	3.75%
Annual increase or decrease in assumed medical care cost trend rate	1.00%
Total accumulated benefit obligation for the pension plans	7,400,000,000	6,700,000,000
Period over which company has elected to amortize changes in the market value of all plan assets	5 years
Period at which the external investment managers typically send valuations to both the custodian and to the company after the quarter end	90 days
Period over which performance of extensive study based on projections of both assets and liabilities for determining optimal asset allocation for pension fund			10 years
Pension Plans Defined Benefit [Member]
Additional Retirement Benefits (Textual) [Abstract]
Expected postretirement trust contributions	0
Projected benefit obligations	8,079,000,000	7,223,000,000	6,758,000,000
Total matching contributions	34,000,000	644,000,000
Retirement Benefits (Textual) [Abstract]
Discount rate on net periodic benefit costs	4.98%	5.52%	5.93%
Other Postretirement Benefits [Member]
Additional Retirement Benefits (Textual) [Abstract]
Expected postretirement trust contributions	31,000,000
Projected benefit obligations	1,787,000,000	1,752,000,000	1,759,000,000
Total matching contributions	54,000,000	66,000,000
Retirement Benefits (Textual) [Abstract]
Discount rate on net periodic benefit costs	4.88%	5.40%	5.83%
Qualified Pension Plans [Member]
Additional Retirement Benefits (Textual) [Abstract]
Projected benefit obligations	7,500,000,000
Non Qualified Pension Plans [Member]
Additional Retirement Benefits (Textual) [Abstract]
Projected benefit obligations	500,000,000
Employee Saving Plan [Member]
Additional Retirement Benefits (Textual) [Abstract]
Matching limit of contribution by employer	85.00%
Maximum limit of contribution of employees base salary	6.00%
Total matching contributions	$ 78,000,000	$ 76,000,000	78,000,000