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Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets $ 568,209 $ 485,965
Marketable Securities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets 515,372 440,395
Equity Investments    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets 52,837 45,570
Level 1    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets 52,837 45,570
Level 1 | Equity Investments    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets 52,837 45,570
Level 2    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets 515,372 440,395
Level 2 | Marketable Securities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Total Assets $ 515,372 $ 440,395