Benefit Plans (Termination and Curtailment Costs Changes for Postretirement Health Care Plans) (Details) (Postretirement Benefit Plan [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued postretirement health care costs	$ 0	$ 11
Prior service cost	(26)	(15)
Termination, settlement and curtailment	$ (26)	$ (4)

Amount of net gain (loss) recognized in net periodic benefit cost due to settlements and curtailments. Curtailments result from an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services. Settlements result from 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, but are not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contracts to cover vested benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(7)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration