Basis of Presentation (Unaudited) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Changes in contract estimates, increase in earnings from continuing operations	$ 214,000,000	$ 196,000,000	$ 701,000,000	$ 541,000,000
Changes in contract estimates, increase in earnings from continuing operations, per diluted share	$ 0.55	$ 0.45	$ 1.79	$ 1.22
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unamortized benefit plan costs, tax benefit	2,184,000,000		2,184,000,000		2,289,000,000
Unamortized benefit plan costs, net of tax benefit of $2,184 as of September 30, 2012 and $2,289 as of December 31, 2011,	(3,333,000,000)		(3,333,000,000)		(3,487,000,000)
Cumulative translation adjustment	(1,000,000)		(1,000,000)		(4,000,000)
Net unrealized gain on marketable securities and cash flow hedges, net of tax expense	0		0		1,000,000
Accumulated other comprehensive loss	(3,334,000,000)		(3,334,000,000)		(3,490,000,000)
Net after-tax actuarial loss amounts	$ 3,700,000,000		$ 3,700,000,000		$ 3,900,000,000