Annual report pursuant to Section 13 and 15(d)

Sale of Investment in Software Company (Details)

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Sale of Investment in Software Company (Details) - USD ($)
12 Months Ended
Oct. 31, 2018
Jul. 06, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Equity Securities without Readily Determinable Fair Value [Line Items]          
Gain on sale of BriefCam, Ltd.     $ 41,000 $ 6,602,000 $ 0
BriefCam, Canon Inc          
Equity Securities without Readily Determinable Fair Value [Line Items]          
Proceeds from Sale of Other Investments $ 100,000 $ 9,678,000      
Gain on sale of BriefCam, Ltd.     $ 41,000 6,602,000  
Briefcam Ltd.          
Equity Securities without Readily Determinable Fair Value [Line Items]          
Investment carrying value       $ 3,100,000  
Maximum | Briefcam Ltd.          
Equity Securities without Readily Determinable Fair Value [Line Items]          
Minority ownership interest (as a percent)   20.00%