Concentrations (Details)	3 Months Ended
	Mar. 31, 2014 item	Mar. 31, 2013 item
Concentrations
Number of areas in which operations are concentrated	1
Three government customers
Concentrations
Number of customers	3	3
Two individual commercial customers
Concentrations
Number of customers	2
One individual commercial customer
Concentrations
Number of customers		1
Total revenues | Customer | U.S. Government
Concentrations
Percentage of revenue	47.20%	67.70%
Total revenues | Customer | Three government customers
Concentrations
Percentage of revenue	34.80%	57.90%
Total revenues | Customer | Two individual commercial customers
Concentrations
Percentage of revenue	51.70%
Total revenues | Customer | One individual commercial customer
Concentrations
Percentage of revenue		31.10%