Basis of Presentation (Unaudited) (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Changes in contract estimates, increase in earnings from continuing operations	$ 236,000,000	$ 214,000,000	$ 657,000,000	$ 701,000,000
Changes in contract estimates, increase in earnings from continuing operations, per diluted share	$ 0.66	$ 0.55	$ 1.80	$ 1.79
Accumulated Other Comprehensive Loss
Unamortized benefit plan costs, net of tax benefit of $2,990 as of September 30, 2013, and $3,149 as of December 31, 2012	(4,553,000,000)		(4,553,000,000)		(4,790,000,000)
Cumulative translation adjustment	12,000,000		12,000,000		4,000,000
Net unrealized loss on marketable securities and cash flow hedges, net of tax benefit	(2,000,000)		(2,000,000)		(1,000,000)
Total accumulated other comprehensive loss	(4,543,000,000)		(4,543,000,000)		(4,787,000,000)
Unamortized benefit plan cost, tax benefit			2,990,000,000		3,149,000,000
Unamortized benefit plan costs, reclassified from other comprehensive income to net earnings	78,000,000	50,000,000	237,000,000	154,000,000
Unamortized benefit plan costs, net actuarial losses, after-tax	$ 4,800,000,000		$ 4,800,000,000		$ 5,100,000,000