Contracts in Process - General & Administrative, Independent Research & Development and Bid & Proposal Costs (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Inventories [Line Items]
Amounts included in inventoried contract costs at beginning of the year	$ 91	$ 97	$ 72
Add: IRAD and B&P costs incurred	336	314	306
Other G&A costs incurred	896	824	836
Total contract costs incurred	1,232	1,138	1,142
Less: Amounts charged to cost of sales	(1,213)	(1,144)	(1,117)
Amounts included in inventoried contract costs at end of the year	$ 110	$ 91	$ 97