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Investment in Affiliate (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2020
Schedule of Investments [Line Items]    
SVTP Preferred Shares   1,879,699
Discontinued Operation, Ownership Interest after Disposal 19.90%  
Investments in and Advances to Affiliates, at Fair Value   $ 2.1