Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Additional Information (Details)

v3.21.2
Fair Value Measurements - Additional Information (Details) - USD ($)
 3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Estimated fair value of equity securities $ 35,280,000   $ 35,280,000   $ 41,644,000
Unrealized gain (loss) on equity securities 4,325,000 $ 48,860,000 (6,364,000) $ 48,860,000  
Vaxcyte, Inc. | Vaxcyte Common Stock          
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Estimated fair value of equity securities 35,300,000   35,300,000    
Unrealized gain (loss) on equity securities $ 4,300,000   $ (6,400,000)    
Equity Securities | Vaxcyte, Inc. | Vaxcyte Common Stock          
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Number of shares held 1,567,324   1,567,324    
Fair Value Measurements Recurring          
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Securities held $ 320,282,000   $ 320,282,000   366,617,000
Fair Value Measurements Recurring | Level 3          
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Securities held $ 0   $ 0   $ 0