Fair Value Measurements - Categorization of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	$ 1,462,688	$ 1,392,169
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	1,462,688	1,390,584
Cash and Cash Equivalents	863,078	588,321
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	1,585
Cash and Cash Equivalents	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	0
Cash and Cash Equivalents	0	0
Debt Securities Carried by EGL
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	459,916	476,778
Debt Securities Carried by EGL \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	459,916	476,778
Debt Securities Carried by EGL \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	0
Debt Securities Carried by EGL \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	0
Other Debt and Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	824,069	753,247
Other Debt and Equity Securities \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents	9,967	8,557
Other Debt and Equity Securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	824,069	753,247
Other Debt and Equity Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	0
Other Debt and Equity Securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	0
Investment Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	178,703	160,559
Investment Funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	178,703	160,559
Investment Funds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	0	0
Investment Funds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value	$ 0	0
Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value		1,585
Other \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value		0
Other \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value		1,585
Other \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured At Fair Value		$ 0