Annual report pursuant to Section 13 and 15(d)

Balance Sheet Account Details - Narrative (Details)

v3.20.4
Balance Sheet Account Details - Narrative (Details)
$ / shares in Units, $ in Millions
Dec. 31, 2020
USD ($)
position
$ / shares
Dec. 31, 2019
USD ($)
Aug. 31, 2014
$ / shares
Schedule of Investments [Line Items]      
Investment in Viking common stock $ 32.8 $ 48.4  
Warrants $ 1.5    
Exercise price of warrants (USD per share) | $ / shares $ 1.50   $ 125.08
Number of positions in an unrealized loss position | position 14    
Investment in warrants      
Schedule of Investments [Line Items]      
Warrants investments in Viking $ 6.3 $ 9.9