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Composition of Certain Financial Statement Captions (Other Assets) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]      
Amortization expense for certain other assets $ 230 $ 231 $ 218