Annual report pursuant to Section 13 and 15(d)

Nature Of Operations And Summary Of Significant Accounting Policies (Details)

v3.10.0.1
Nature Of Operations And Summary Of Significant Accounting Policies (Details) - USD ($)
 12 Months Ended
Jan. 18, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Contract liabilities   $ 90,000 $ 360,000  
Revenue recognized from satisfaction of performance obligations   554,000    
Accounts receivable   35,943,000 35,817,000  
Accounts receivable,allowance   392,000 382,000  
Accounts receivable write-off   0 0 $ 0
Aggregate cost of tender offer   $ 5,687,000 17,000 5,078,000
Dividend annualized   $ 0.10    
Dividend per quarter   $ 0.025    
Dividends   $ (1,488,000)    
Dividends per share   $ 0.05    
Goodwill impairment   $ 0 0 0
Indefinite-lived intangible asset impairment   $ 0 0 0
Stock options, term of expiration   10 years    
Advertising expense   $ 4,016,000 3,951,000 2,605,000
Cooperative advertising expense   338,000 537,000 741,000
Reserve for product warranty   1,032,000 987,000  
Warranty claims   999,000 949,000 1,051,000
Research and development costs   $ 9,471,000 $ 7,984,000 $ 6,598,000
Modified Dutch Auction [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Number of shares acquired in tender offer   417,237    
Per share cost of tender offer   $ 8.00    
Aggregate cost of tender offer   $ 3,338,000    
Authorized Stock Repurchase Program [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Aggregate cost of tender offer   2,349,000    
Minimum [Member] | ASU 2016-02 [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Lease liability   1,000,000    
ROU asset   1,000,000    
Maximum [Member] | ASU 2016-02 [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Lease liability   1,500,000    
ROU asset   $ 1,500,000    
Building Improvements [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Estimated useful Life   20 years    
Machinery and Equipment [Member] | Minimum [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Estimated useful Life   3 years    
Machinery and Equipment [Member] | Maximum [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Estimated useful Life   10 years    
Furniture and Fixtures [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Estimated useful Life   5 years    
Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Concentration risk, percentage   12.00% 14.00% 16.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Concentration risk, percentage   15.00%    
Subsequent Event [Member]        
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]        
Dividends $ 1,488,000      
Dividends per share $ 0.025      
Dividend date declared Jan. 18, 2019      
Dividend date of record Jan. 29, 2019      
Dividend date to be paid Feb. 08, 2019