Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - General Information (Details)

v3.19.2
Summary of Significant Accounting Policies - General Information (Details)
12 Months Ended
Jun. 05, 2018
USD ($)
payment
Oct. 13, 2017
USD ($)
payment
Mar. 31, 2019
USD ($)
shares
Mar. 31, 2018
USD ($)
shares
Changes in the accounts receivable allowances        
Accounts receivable allowance, beginning balance     $ 5,744,000 $ 6,845,000
Additions charged to costs and expenses     (345,000) (1,099,000)
Bad debt write-off     (101,000) (2,000)
Accounts receivable allowance, ending balance     5,298,000 5,744,000
Inventories        
Inventory allowance     3,887,000 5,494,000
Long-Lived Assets        
Impairment     $ 0  
Revenue        
Practical expedient to disclose only the value of unsatisfied performance obligations for contracts with an original expected length greater than one year     true  
Practical expedient to expense costs as incurred for costs to obtain a contract when the amortization period would have been one year or less     true  
Research and Development ("R&D")        
Total offsets to R&D expenses     $ 0  
Risk Concentrations        
Aggregate balances that exceed insurance coverage     29,100,000  
Recovery of bad debt     345,000 $ 1,099,000
Accounts Receivable Assignment Agreement | Turbine International, LLC. and MTE Service        
Changes in the accounts receivable allowances        
Additions charged to costs and expenses     (1,000,000)  
Risk Concentrations        
Recovery of bad debt     1,000,000  
Total collections on accounts receivable allowance     1,500,000  
Total consideration receivable   $ 2,500,000    
Number of payments to be received | payment   3    
Payment not yet received     $ 400,000  
Promissory Note Agreement | Turbine International, LLC. and MTE Service        
Risk Concentrations        
Total consideration receivable   $ 3,800,000    
Term of payments   3 years    
Number of payments to be received | payment   35    
Amended Note Agreement | Turbine International, LLC. and MTE Service        
Risk Concentrations        
Total consideration receivable $ 3,800,000      
Term of payments 3 years      
Number of payments to be received | payment 13      
Stock options        
Net Loss Per Common Share        
Options outstanding (in shares) | shares     174,944 212,392
Restricted stock units        
Net Loss Per Common Share        
Options outstanding (in shares) | shares     2,400,000 2,000,000
Warrants        
Net Loss Per Common Share        
Antidilutive securities excluded from diluted net loss per common share computations | shares     6,800,000 8,500,000
BPC        
Risk Concentrations        
Total collections on accounts receivable allowance     $ 1,800,000  
Number of payments to be received | payment 5      
Accounts receivable $ 1,500,000   $ 4,800,000  
Revenue | Customer concentrations | E-Finity        
Risk Concentrations        
Concentration percentage     13.00% 16.00%
Revenue | Customer concentrations | Horizon        
Risk Concentrations        
Concentration percentage     12.00%  
Net accounts receivable | Customer concentrations | E-Finity        
Risk Concentrations        
Concentration percentage     10.00% 18.00%
Net accounts receivable | Customer concentrations | Serba        
Risk Concentrations        
Concentration percentage       20.00%
Net accounts receivable | Customer concentrations | Supernova        
Risk Concentrations        
Concentration percentage       10.00%
Net accounts receivable | Customer concentrations | Reliable Secure Power Systems        
Risk Concentrations        
Concentration percentage     14.00%  
Minimum        
Depreciation and Amortization        
Estimated useful lives     2 years  
Maximum        
Depreciation and Amortization        
Estimated useful lives     10 years  
Warranty        
Warranty period     24 months