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Non-Marketable Investments - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Equity Method Investments And Joint Ventures [Abstract]      
Carrying value of investment in privately-held companies $ 169,500,000 $ 55,000,000.0  
Impairment on investment 29,500,000   $ 7,200,000
Gain on non-marketable investments $ 42,400,000 $ 20,800,000