Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets, Net and Goodwill (Schedule of Identifiable Intangible Assets) (Details)

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Intangible Assets, Net and Goodwill (Schedule of Identifiable Intangible Assets) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Summary of Identifiable Intangible Assets [Line Items]      
Gross carrying amount $ 37,198 $ 37,198 $ 37,198
Accumulated amortization (31,973) (29,769) (31,561)
Net carrying amount 5,225 7,429 5,637
Intangible assets not subject to amortization 97,921 115,421 97,921
Intangible Assets, Net (Excluding Goodwill), Total 103,146 122,850 103,558
Amortization of Intangible Assets 400 700  
Patents And Purchased Technology [Member]      
Summary of Identifiable Intangible Assets [Line Items]      
Gross carrying amount 14,198 14,198 14,198
Accumulated amortization (14,198) (13,644) (14,198)
Customer Relationships [Member]      
Summary of Identifiable Intangible Assets [Line Items]      
Gross carrying amount 23,000 23,000 23,000
Accumulated amortization $ (17,775) $ (16,125) $ (17,363)