Basis of Presentation - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 25, 2015	Sep. 26, 2014
Accounting Policies [Abstract]
Percentage of sales accounted for under contract accounting standards	46.00%
Percentage of fixed-price type contracts	40.00%
Percentage of cost-plus type contracts	6.00%
Period of performance for contracts accounted for under the percentage-of-completion method of accounting, minimum	1 year
Aggregate net changes in contract estimates amounted to increases of consolidated operating income	$ 52	$ 71
Increases in percentage of aggregate net changes in contract estimates of segment operating income	8.00%
Increases in percentage of aggregate net changes in contract estimates of consolidated operating income	34.00%	9.00%