Segment Information - Net Sales to Principal Customers (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net sales	$ 3,208	$ 2,940	$ 3,019	$ 2,957	$ 3,234	$ 3,002	$ 3,189	$ 3,197	$ 12,124	$ 12,622	$ 13,107
Operating Segments [Member] | U.S. Government Agencies [Member]
Segment Reporting Information [Line Items]
Net sales									8,584	9,186	9,986
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net sales									1,693	1,689	1,658
Operating Segments [Member] | Foreign Governments [Member]
Segment Reporting Information [Line Items]
Net sales									$ 1,847	$ 1,747	$ 1,463