Customers Revenue and Receivables (Billed and Unbilled) (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Customer Concentration Risk | Revenue | U.S Government Agencies and Departments | Government Segment
Concentration Risk [Line Items]
Concentration of risk percentage	22.00%	32.00%	44.00%
Customer Concentration Risk | Revenue | Verizon Wireless | Commercial Segment
Concentration Risk [Line Items]
Concentration of risk percentage	16.00%	16.00%	13.00%
Credit Concentration Risk | Receivables (billed and unbilled) | U.S Government Agencies and Departments | Government Segment
Concentration Risk [Line Items]
Concentration of risk percentage	31.00%	10.00%
Credit Concentration Risk | Receivables (billed and unbilled) | Verizon Wireless | Commercial Segment
Concentration Risk [Line Items]
Concentration of risk percentage	15.00%	17.00%
Credit Concentration Risk | Receivables (billed and unbilled) | A T T | Commercial Segment
Concentration Risk [Line Items]
Concentration of risk percentage		13.00%