Customers Revenue and Receivables (Billed and Unbilled) (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Customer Concentration Risk | Revenue | U.S Government Agencies and Departments | Government Segment
Concentration Risk [Line Items]
Concentration of risk percentage	26.00%	37.00%	21.00%	37.00%
Customer Concentration Risk | Revenue | Customer A | Commercial Segment
Concentration Risk [Line Items]
Concentration of risk percentage	18.00%	15.00%	16.00%	15.00%
Credit Concentration Risk | Receivables (billed and unbilled) | U.S Government Agencies and Departments | Government Segment
Concentration Risk [Line Items]
Concentration of risk percentage			33.00%	35.00%
Credit Concentration Risk | Receivables (billed and unbilled) | Customer A | Commercial Segment
Concentration Risk [Line Items]
Concentration of risk percentage				18.00%
Credit Concentration Risk | Receivables (billed and unbilled) | Customer B | Commercial Segment
Concentration Risk [Line Items]
Concentration of risk percentage			12.00%	14.00%