Benefit Plans (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	0 Months Ended
Mar. 31, 2013	Mar. 31, 2013 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Jan. 02, 2013 Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 8			$ 350
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year, Description		20	40

The increase in the fair value of plan assets from contributions made by the employer.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration