Concentrations (Details)	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011 item
Concentrations
Number of areas in which operations are concentrated	1
U.S. Government
Concentrations
Number of customers	4
One individual commercial customer
Concentrations
Number of customers	1	1
Three government customers
Concentrations
Number of customers		3
Total revenues | Customer | U.S. Government
Concentrations
Percentage of revenue	40.50%	38.40%
Total revenues | Customer | One individual commercial customer
Concentrations
Percentage of revenue	57.00%	58.00%
Total revenues | Customer | Three government customers
Concentrations
Percentage of revenue		34.20%
Total revenues | Customer | Four government customers
Concentrations
Percentage of revenue	38.20%