Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Narrative) (Details)

v3.10.0.1
Summary of Significant Accounting Policies (Narrative) (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
segment
$ / shares
shares
Dec. 31, 2017
USD ($)
shares
Summary of Significant Accounting Policies [Line Items]    
Number of segments | segment 4  
Cash and cash equivalents $ 11,056,426 $ 12,453,663
Money market funds $ 8,428,000  
Value of the investment in short-term money market funds sought to be preserved (in dollars per share) | $ / shares $ 1.00  
Depreciation $ 2,203,000 3,156,000
Product warranty period 5 years  
Research and development costs $ 3,786,000 3,639,000
Maximum matching percentage by employer 6.00%  
Contributions to the plan $ 450,000 450,000
Dilutive effect $ 0 $ 0
Employee Stock Option [Member]    
Summary of Significant Accounting Policies [Line Items]    
Shares not included in the computation of diluted earnings per share | shares 1,320,492 1,144,159
Deferred Stock Awards [Member]    
Summary of Significant Accounting Policies [Line Items]    
Shares not included in the computation of diluted earnings per share | shares 265,491 181,224