Concentrations (Details)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Concentrations
Number of areas in which operations are concentrated	1
Three government customers
Concentrations
Number of customers	3
Two government customers
Concentrations
Number of customers		2
Total revenues | Customer | U.S. Government
Concentrations
Percentage of revenue	67.70%	42.70%
Total revenues | Customer | Three government customers
Concentrations
Percentage of revenue	57.90%
Total revenues | Customer | Two government customers
Concentrations
Percentage of revenue		38.90%