Summary of Significant Accounting Policies (Details 1) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012 Sectors	Dec. 31, 2011	Dec. 31, 2010
Summary of Significant Accounting Policies (Amounts in paragraphs)
Number of operating segments	4
Aggregate net changes in contract estimates leading Increase in earnings from continuing operations	$ 985	$ 738	$ 675
Aggregate net changes in contract estimates leading Increase in earnings from continuing operations (in dollars per diluted share)	$ 2.53	$ 1.70	$ 1.46
Research and development expenses	520	543	580
Cash surrender value of life insurance	$ 271	$ 257
Minimum
Summary of Significant Accounting Policies (Amounts in paragraphs)
Stock awards, award vesting period	3 years

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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