Pension and Other Postretirement Benefits - Plan Amendments (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	3 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2013 Retiree Health Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Pre-tax curtailment gain or settlement loss	$ 19	$ (6)	$ 19
After-tax curtailment gain or settlement loss	12	(4)	12
Increase (decrease) to liability for defined benefit plans resulting from plan amendments			(57)
Increase (decrease) to shareholders' equity resulting from plan amendments			$ 37

The amount of increase or decrease due to a change in the terms of an existing plan or the initiation of a new plan. A plan amendment may increase or decrease benefits, including those attributed to years of service already rendered.

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+ Details

- Definition

Before tax amount of the income statement impact of the reclassification adjustment for prior service costs recognized as a component of net period benefit cost.

+ References

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+ Details

- Definition

Net of tax amount of the income statement impact of the reclassification adjustment for prior service costs recognized as a component of net period benefit cost.

+ References

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+ Details