Fair Value Measurements - Information about Financial Assets Measured at Fair Value on Recurring Basis Based on Three-Tier Fair Value Hierarchy (Details) - Fair Value Measurements Recurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total equity securities, debt securities and cash equivalents	$ 823,981	$ 833,206
U.S. Government Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	365,770	332,048
U.S. Agency Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	226,717	156,688
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	75,138	194,149
U.S. Treasury Bills
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	69,250	69,798
Money Market Accounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents fair value disclosure	38,291	27,455
Redeemable Preferred Stock Investment
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	20,438	12,385
Preferred Stock Of Privately Held Company
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	15,000	15,000
Municipal Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	12,685	22,673
Yankee Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	692	3,010
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total equity securities, debt securities and cash equivalents	107,541	97,253
Level 1 | U.S. Treasury Bills
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	69,250	69,798
Level 1 | Money Market Accounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents fair value disclosure	38,291	27,455
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total equity securities, debt securities and cash equivalents	681,002	708,568
Level 2 | U.S. Government Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	365,770	332,048
Level 2 | U.S. Agency Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	226,717	156,688
Level 2 | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	75,138	194,149
Level 2 | Municipal Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	12,685	22,673
Level 2 | Yankee Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	692	3,010
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total equity securities, debt securities and cash equivalents	35,438	27,385
Level 3 | Redeemable Preferred Stock Investment
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	20,438	12,385
Level 3 | Preferred Stock Of Privately Held Company
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total debt securities	$ 15,000	$ 15,000