Stock-Based Compensation - Company's Stock Option Activity and Changes (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Y
Schedule Of Stock Option Activity [Line Items]
Beginning Balance, Aggregate Intrinsic Value Outstanding	$ 8
Ending Balance, Aggregate Intrinsic Value Outstanding	23
Vested and Expected to Vest, Aggregate Intrinsic Value	23
Exercisable, Aggregate Intrinsic Value	$ 16
Beginning Balance, Weighted Average Remaining Contractual Term Outstanding	5.9
Ending Balance, Weighted Average Remaining Contractual Term Exercisable Outstanding	5.8
Vested and Expected to Vest, Weighted Average Remaining Contractual Term	5 years 9 months 18 days
Exercisable, Weighted Average Remaining Contractual Term	4 years 8 months 12 days
Beginning Balance, Weighted Average Exercise Price Outstanding	$ 79.55
Options granted, Weighted Average Exercise Price	$ 70.42
Options exercised, Weighted Average Exercise Price	$ 53.82
Options forfeited, Weighted Average Exercise Price	$ 80.55
Engility spin-off adjustments	$ 83.24
Ending Balance, Weighted Average Exercise Price Outstanding	$ 76.57
Vested and Expected to Vest, Weighted Average Exercise Price	$ 76.57
Exercisable, Weighted Average Exercise Price	$ 78.03
Beginning Balance, Number of Options Outstanding	4,623,600
Options granted, Number of Options	789,900
Options exercised, Number of Options	(369,600)
Options forfeited, Number of Options	(207,100)
Engility spin-off adjustments	153,100
Ending Balance, Number of Options Outstanding	4,989,900
Vested and Expected to Vest, Number of Options	4,966,900
Exercisable, Number of Options	3,531,100