Fair Value Measurements - Ltd Partnerships (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 93,433	$ 82,725
Limited Partnership Funds - Middle Market
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments	3 years	4 years
Limited Partnership Funds - Middle Market | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 34,832	$ 34,858
Limited Partnership Funds - Middle Market | Unfunded Loan Commitment | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 1,669	$ 3,452
Limited Partnership Funds - Global
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments	0 years	0 years
Limited Partnership Funds - Global | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 11,908	$ 10,345
Limited Partnership Funds - Global | Unfunded Loan Commitment | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	0	0
Limited Partnership Funds - Late-Stage Growth | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 25,431	$ 20,524
Limited Partnership Funds - Late-Stage Growth | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments	4 years	4 years
Limited Partnership Funds - Late-Stage Growth | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments	6 years	6 years
Limited Partnership Funds - Late-Stage Growth | Unfunded Loan Commitment | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 10,102	$ 14,271
Limited Partnership Funds - Infrastructure
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments		10 years
Limited Partnership Funds - Infrastructure | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 20,996	$ 16,733
Limited Partnership Funds - Infrastructure | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments	9 years
Limited Partnership Funds - Infrastructure | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Maturity Timeframe of Other Long-Term Investments	11 years
Limited Partnership Funds - Infrastructure | Unfunded Loan Commitment | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 6,345	9,576
Limited Partnership Funds [Member] | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	93,167	82,460
Limited Partnership Funds [Member] | Unfunded Loan Commitment | Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	$ 18,116	$ 27,299