Basis of Presentation (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified			3 Months Ended	9 Months Ended
Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Contracts Accounted for under Percentage of Completion	Sep. 30, 2013 Contracts Accounted for under Percentage of Completion	Sep. 30, 2014 Contracts Accounted for under Percentage of Completion	Sep. 30, 2013 Contracts Accounted for under Percentage of Completion
Change in Accounting Estimate
Increase (decrease) in operating income due to net cumulative catch-up adjustments			$ 46	$ 2	$ 154	$ 67
Increase (decrease) in diluted earnings per share due to net cumulative catch-up adjustments			$ 0.61	$ 0.02	$ 2.03	$ 0.86
Assets held in rabbi trusts	$ 43	$ 40

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(b))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_AssetsHeldInTrust
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant