Annual report pursuant to Section 13 and 15(d)

Concentrations of Credit Risk and Major Customers (Details)

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Concentrations of Credit Risk and Major Customers (Details)
12 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2010
Concentrations of Credit Risk and Major Customers      
Number of major customers 3    
Total Revenue | Foreign customers
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 26.00% 32.00% 27.00%
Total Revenue | State and local government agencies
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 61.00%    
Total Revenue | Federal government agencies
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 9.00%    
Total Revenue | Other sources, such as commercial customers
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 4.00%    
Total Revenue | Australia
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 16.00% 19.00% 16.00%
Total Revenue | State of Texas
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 18.00% 16.00% 16.00%
Total Revenue | State of California
     
Concentrations of Credit Risk and Major Customers      
Revenue from major customers (as a percent) 10.00% 11.00% 12.00%