Basis of Presentation (Details) (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Mar. 31, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Accumulated Other Comprehensive Loss
Cumulative translation adjustment	$ 2			$ 2		$ 0
Net unrealized gain on marketable securities and cash flow hedges, net of tax expense of $2 as of September 30, 2011, and $3 as of December 31, 2010	3			3		5
Unamortized benefit plan costs, net of tax benefit of $1410 as of September 30, 2011 and $1,801 as of December 31, 2010	(2,181)			(2,181)		(2,762)
Accumulated other comprehensive loss	(2,176)			(2,176)		(2,757)
Accumulated Other Comprehensive Loss (Parenthetical)
Tax expense on net unrealized gain on marketable securities and cash flow hedges	2			2		3
Tax benefit on unamortized benefit plan costs	1,410			1,410		1,801
Accumulated Other Comprehensive Loss (Amounts in paragraphs)
Change in unamortized benefit plan costs, net of tax	22		39	57	118
Spin-off of Shipbuilding business		524
Net after-tax actuarial loss amounts	$ 2,164			$ 2,164		$ 2,771
Percentage threshold for excess gains or losses that are subject to amortization				10.00%
Average future service period of employees				10 years