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 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Estimated fair value of equity securities $ 39,763,000   $ 39,763,000   $ 41,644,000
Unrealized gain (loss) on equity securities 4,483,000 $ 29,778,000 (1,881,000) $ 78,638,000  
Vaxcyte, Inc. | Vaxcyte Common Stock          
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]          
Estimated fair value of equity securities 39,800,000   39,800,000    
Unrealized gain (loss) on equity securities $ 4,500,000   $ (1,900,000)    
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 $ 293,381,000   $ 293,381,000   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