Annual report pursuant to Section 13 and 15(d)

Prepaid Expenses And Other Current Assets & Patents And Intangible Assets - Schedule of Intangible Assets (Details)

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Prepaid Expenses And Other Current Assets & Patents And Intangible Assets - Schedule of Intangible Assets (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]    
Patents $ 26,069 $ 26,552
Less: accumulated amortization (20,562) (18,804)
Intangible assets, net $ 5,507 $ 7,748