Concentrations (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Concentrations
Number of areas in which operations are concentrated			1
Two government customers
Concentrations
Number of customers	2	2
One individual commercial customer
Concentrations
Number of customers		1
Two individual commercial customers
Concentrations
Number of customers	2
Total revenues | Customer | U.S. Government
Concentrations
Percentage of revenue	45.80%	34.30%	51.90%	35.20%
Total revenues | Customer | Two government customers
Concentrations
Percentage of revenue	30.90%	26.10%
Total revenues | Customer | One individual commercial customer
Concentrations
Percentage of revenue		64.00%
Total revenues | Customer | Two individual commercial customers
Concentrations
Percentage of revenue	53.20%