Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details)

v3.7.0.1
Summary of Significant Accounting Policies (Details) - USD ($)
shares in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Changes in the accounts receivable allowances        
Accounts receivable allowance, beginning balance   $ 8,909,000 $ 11,041,000  
Accounts receivable allowances   (1,525,000) (1,459,000)  
Deductions   (539,000) (673,000)  
Accounts receivable allowance, ending balance $ 11,041,000 $ 6,845,000 8,909,000 $ 11,041,000
Revenue        
Term for advance payment from shipment of sales   90 days    
Research and Development ("R&D")        
Total offsets to R&D expenses   $ 0 200,000  
Risk Concentrations        
Aggregate balances that exceed insurance coverage   19,000,000    
Provision for doubtful accounts receivable   (1,525,000) (1,459,000)  
Bad debt recovery   $ 1,500,000 $ 1,500,000  
Stock options        
Net Loss Per Common Share        
Options outstanding (in shares)   0.3 0.5  
Restricted stock        
Net Loss Per Common Share        
Outstanding restricted stock units (in shares)   0.3 0.3  
Warrants        
Net Loss Per Common Share        
Antidilutive securities excluded from diluted net loss per common share computations   10.4    
BPC        
Changes in the accounts receivable allowances        
Accounts receivable allowances 7,100,000      
Risk Concentrations        
Provision for doubtful accounts receivable $ 7,100,000      
EMI        
Changes in the accounts receivable allowances        
Accounts receivable allowances       2,600,000
Risk Concentrations        
Provision for doubtful accounts receivable       $ 2,600,000
Sales | Customer concentrations | Horizon Power Systems        
Risk Concentrations        
Concentration percentage   11.00% 15.00%  
Sales | Customer concentrations | E-Finity        
Risk Concentrations        
Concentration percentage   14.00% 11.00%  
Sales | Customer concentrations | DTC        
Risk Concentrations        
Concentration percentage     10.00%  
Sales | Customer concentrations | Optimal        
Risk Concentrations        
Concentration percentage     10.00%  
Net accounts receivable | Credit concentration | E-Finity        
Risk Concentrations        
Concentration percentage   29.00%    
Net accounts receivable | Credit concentration | DTC        
Risk Concentrations        
Concentration percentage   12.00% 28.00%  
Net accounts receivable | Credit concentration | Optimal        
Risk Concentrations        
Concentration percentage     11.00%  
Net accounts receivable | Credit concentration | Reliable Secure Power Systems        
Risk Concentrations        
Concentration percentage   10.00% 10.00%  
Net accounts receivable | Credit concentration | Regale Energy Zrt        
Risk Concentrations        
Concentration percentage     10.00%  
Backlog        
Long-Lived Assets        
Finite-lived intangible asset amount written off   $ 17,000 $ 100,000  
TA100        
Inventories        
Inventory allowance   500,000 800,000  
TA100 | Backlog        
Long-Lived Assets        
Finite-lived intangible asset amount written off   $ 17,000 $ 100,000  
Minimum        
Depreciation and Amortization        
Estimated useful lives   2 years    
Maximum        
Depreciation and Amortization        
Estimated useful lives   10 years    
Warranty        
Warranty period   24 months