Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Narrative) (Details)

v3.21.1
Summary of Significant Accounting Policies (Narrative) (Details)
12 Months Ended
Dec. 31, 2020
USD ($)
segment
$ / shares
shares
Dec. 31, 2019
USD ($)
shares
Summary of Significant Accounting Policies [Line Items]    
Number of segments | segment 2  
Cash and cash equivalents $ 13,092,484 $ 13,928,504
Money market funds $ 9,424,000  
Value of the investment in short-term money market funds sought to be preserved (in dollars per share) | $ / shares $ 1.00  
Depreciation $ 757,000 1,028,000
Product warranty period 5 years  
Research and development costs $ 2,808,000 3,600,000
Maximum matching percentage by employer 6.00%  
Contributions to the plan $ 371,000 $ 401,000
Dilutive shares | shares 0 65,163
Employee Stock Option [Member]    
Summary of Significant Accounting Policies [Line Items]    
Shares not included in the computation of diluted earnings per share | shares 697,201 860,539
Deferred Stock Awards [Member]    
Summary of Significant Accounting Policies [Line Items]    
Shares not included in the computation of diluted earnings per share | shares 110,308 178,278