Employee Benefit Plans (Change in Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Fair values of the company's pension plan assets
Employer contributions	$ 200
Pension Benefits [Member]
Fair values of the company's pension plan assets
Fair value of plan assets - beginning of year	4,513	3,922
Actual return on plan assets	381	613
Employer contributions	201	201
Benefits paid	(230)	(210)
Expenses paid	(13)	(12)
Settlements	(3)	0
Foreign exchange adjustment	1	(1)
Fair value of plan assets - end of year	4,850	4,513
Funded status — end of year	(1,230)	(952)
Other Postretirement Benefits [Member]
Fair values of the company's pension plan assets
Fair value of plan assets - beginning of year	203	190
Actual return on plan assets	17	13
Employer contributions	0	0
Benefits paid	0	0
Expenses paid	0	0
Settlements	0	0
Foreign exchange adjustment	0	0
Fair value of plan assets - end of year	220	203
Funded status — end of year	$ (93)	$ (221)

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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+ Details

- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

+ References

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+ Details

- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References+ Details

- Definition

The amount that relates to 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.

+ References

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+ Details