Fair Value Measurement (Investments in LLCs and Limited Partnerships) (Details) $ in Thousands	9 Months Ended
Sep. 30, 2024 USD ($) fund	Dec. 31, 2023 USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 238,159	$ 245,455
Private debt funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Number of limited partners in investment \| fund	2
Number of limited partners to allow redemption by special consent \| fund	1
Private debt funds \| Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidating investments remaining period	3 years
Private debt funds \| Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidating investments remaining period	8 years
Private debt funds \| Investment in unconsolidated subsidiaries
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Contractual Commitments	$ 4,455
Fair Value	$ 15,259	19,886
Long/short equity funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Number of limited partners in investment \| fund	1
Payment period for redemption of LP valued at NAV	30 days
Long/short equity funds \| Investment in unconsolidated subsidiaries
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Contractual Commitments	$ 0
Fair Value	$ 4,151	4,497
Non-public equity funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Number of limited partners in investment \| fund	2
Liquidating investments remaining period	10 years
Non-public equity funds \| Investment in unconsolidated subsidiaries
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Contractual Commitments	$ 32,129
Fair Value	$ 112,675	111,251
Credit funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Number of limited partners in investment \| fund	2
Number of limited partners to allow redemption by special consent \| fund	1
Investment redemption notice period	180 days
Number of limited partners to allow redemption by special consent of partner \| fund	2
Credit funds \| Investment in unconsolidated subsidiaries
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Contractual Commitments	$ 29,614
Fair Value	$ 48,283	55,740
Strategy focused funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Number of limited partners not permitted for redemption \| fund	3
Number of limited partners, redemption allowed with prior notice \| fund	2
Strategy focused funds \| Investment in unconsolidated subsidiaries
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Contractual Commitments	$ 49,427
Fair Value	$ 57,791	$ 54,081

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Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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Remaining period of expected liquidation by investee of underlying asset of investment measured at net asset value per share or unit. In 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

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