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Description of Business and Summary of Significant Accounting Policies (Details) (USD $)
3 Months Ended
Jun. 30, 2013
Mar. 31, 2013
Jun. 30, 2012
Mar. 31, 2012
Cash and Cash Equivalents        
Cash and cash equivalents $ 19,092,000 $ 19,137,000 $ 18,546,000 $ 18,701,000
Cash designated as collateral on performance bonds $ 500,000      
Percentage of cash value of the bonds as collateral 100.00%      
Maximum
       
Costs in Excess of Billings on Uncompleted Contracts        
Expected period for unbilled amounts to be billed and collected 12 months      
Billings in Excess of Costs and Estimated Earnings on Uncompleted Contracts        
Expected period for unearned amounts to be earned 12 months      
Warranty        
Warranty period 3 years      
Maximum | Property and equipment
       
Property and Equipment        
Useful life 8 years      
Minimum
       
Warranty        
Warranty period 1 year      
Minimum | Property and equipment
       
Property and Equipment        
Useful life 3 years