Employee Severance and Termination Costs - Employee Severance and Other Termination Costs Incurred by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 25, 2015	Sep. 26, 2014	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Employee severance and other termination costs	$ 4	$ 3	$ 10	$ 23	$ 30
Electronic Systems [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance and other termination costs	2		4	14
Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance and other termination costs	1	1	3	3
Communication Systems [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance and other termination costs	$ 1	$ 2	$ 3	5
NSS [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance and other termination costs				$ 1