Summary Of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Segment	Dec. 31, 2011	Dec. 31, 2010
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Number of business groups	4
Net increase in operating earnings from the impact of revisions in contract	$ 180	$ 356	$ 350
Net increase in operating earnings per share from the quarterly impact of revisions in contract	$ 0.33	$ 0.63	$ 0.60
Contractual advance	35	170
T AKE Combat Logistics Ship [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Net increase in operating earnings from the impact of revisions in contract	53
Specialist Vehicle [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Net increase in operating earnings from the impact of revisions in contract	$ (32)