Benefit Plans (Schedule of amounts recognized in Other comprehensive income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax
Amounts arising during the period	$ (325)	$ 44	$ 13
Reclassification adjustment relating to prior service cost (credit)	(19)	(16)	(16)
Reclassification adjustment relating to actuarial (gain) loss	25	25	26
Total increase (decrease) in Other comprehensive income	$ (319)	$ 53	$ 23

The change in other comprehensive income due to the amortization of the net prior service costs (credit) into net periodic pension costs.

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+ Details

- Definition

Amounts recognized in other comprehensive income (but not yet recognized in net periodic benefit cost), including the net gain (loss) and net prior service cost (credit) arising during the period. Also includes reclassification adjustments out of other comprehensive income as a result of being recognized as components of net periodic benefit cost for the period. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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+ Details

- Definition

Pretax change 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, that has not been recognized in net periodic benefit cost.

+ References

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+ Details

- Definition

The adjustment out of other comprehensive income for actuarial gains or losses recognized as a component of net periodic benefit cost during the period, after tax.

+ References+ Details