Basis of Presentation (Unaudited) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Changes in contract estimates, increase in earnings from continuing operations	$ 174,000,000	$ 265,000,000
Changes in contract estimates, increase in earnings from continuing operations, per diluted share	$ 0.47	$ 0.67
Accumulated Other Comprehensive Loss
Unamortized benefit plan costs, net of tax benefit of $3,097 as of March 31, 2013, and $3,149 as of December 31, 2012	(4,710,000,000)		(4,790,000,000)
Cumulative translation adjustment	(12,000,000)		4,000,000
Net unrealized gain (loss) on marketable securities and cash flow hedges, net of tax expense of $0 in both 2013 and 2012	(1,000,000)		(1,000,000)
Total accumulated other comprehensive loss	(4,723,000,000)		(4,787,000,000)
Unamortized benefit plan cost tax benefit	3,097,000,000		3,149,000,000
Unamortized benefit plan costs, net actuarial losses, after-tax	5,000,000,000		5,100,000,000
Unamortized benefit plan costs, reclassified from other comprehensive income to net earnings	$ 80,000,000	$ 50,000,000