Segment Information - Net Sales to Principal Customers (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Net sales	$ 13,146	$ 13,158	$ 13,390
U.S. Government agencies [Member]
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Net sales	10,026	10,439	10,803
Commercial [Member]
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Net sales	1,657	1,527	1,446
Allied foreign governments [Member]
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Net sales	$ 1,463	$ 1,192	$ 1,141