Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details)

v3.8.0.1
Summary of Significant Accounting Policies (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Jun. 05, 2018
USD ($)
payment
Oct. 13, 2017
USD ($)
payment
Mar. 31, 2018
USD ($)
shares
Mar. 31, 2018
USD ($)
kW
shares
Mar. 31, 2017
USD ($)
shares
Mar. 31, 2015
USD ($)
Changes in the accounts receivable allowances            
Accounts receivable allowance, beginning balance       $ 6,845 $ 8,909  
Recovery of bad debt       (1,099) (1,525)  
Bad debt write-off       (2) (539)  
Accounts receivable allowance, ending balance     $ 5,744 5,744 6,845  
Inventories            
Inventory allowance     5,494 5,494 6,040  
Long-Lived Assets            
Impairment       $ 0    
Revenue            
Term for advance payment from shipment of sales       90 days    
Research and Development ("R&D")            
Total offsets to R&D expenses       $ 0 0  
Risk Concentrations            
Aggregate balances that exceed insurance coverage     19,200 19,200    
Bad debt recovery       1,099 $ 1,525  
Bridge Bank            
Summary of Significant Accounting Policies            
Restricted cash equivalents for credit facility     5,000 5,000    
Accounts Receivable Agreement | Turbine International, LLC. and MTE Service            
Changes in the accounts receivable allowances            
Recovery of bad debt     (300) (1,000)    
Risk Concentrations            
Bad debt recovery     300 1,000    
Total collections on accounts receivable allowance     $ 1,000 $ 1,000    
Total consideration receivable   $ 2,500        
Number of payments to be received | payment   3        
Promissory Note Agreement | Turbine International, LLC. and MTE Service            
Risk Concentrations            
Total consideration receivable   $ 3,800        
Term of payments   3 years        
Number of payments to be received | payment   35        
Amended Promissory Note Agreement | Turbine International, LLC. and MTE Service | Subsequent event            
Risk Concentrations            
Total consideration receivable $ 3,800          
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     212,392 212,392 314,537  
Warrants            
Net Loss Per Common Share            
Antidilutive securities excluded from diluted net loss per common share computations | shares       8,500,000 10,400,000  
BPC            
Risk Concentrations            
Total collections on accounts receivable allowance     $ 1,800 $ 1,800    
Accounts receivable     $ 5,300 $ 5,300   $ 8,100
BPC | Subsequent event            
Risk Concentrations            
Number of payments to be received | payment 5          
Accounts receivable $ 1,500          
Sales | Customer concentrations | E-Finity            
Risk Concentrations            
Concentration percentage       16.00% 14.00%  
Sales | Customer concentrations | Horizon Power Systems            
Risk Concentrations            
Concentration percentage         11.00%  
Net accounts receivable | Customer concentrations | E-Finity            
Risk Concentrations            
Concentration percentage       18.00% 29.00%  
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 | DTC            
Risk Concentrations            
Concentration percentage         12.00%  
Net accounts receivable | Customer concentrations | Reliable Secure Power Systems            
Risk Concentrations            
Concentration percentage         10.00%  
TA100            
Inventories            
Inventory allowance         $ 500  
Capacity of microturbine (in kW) | kW       100    
Minimum            
Depreciation and Amortization            
Estimated useful lives       2 years    
Maximum            
Depreciation and Amortization            
Estimated useful lives       10 years    
Warranty            
Warranty period       24 months