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Equity-Method Eligible Investments - Carrying Values of Equity Method Eligible Investments Recorded within Other Long-Term Investments (Details) - USD ($) $ in Millions | Sep. 30, 2022 | Dec. 31, 2021 | May 07, 2020 | May 06, 2020
--- | --- | --- | --- | ---
Investments in unconsolidated affiliates |  |  |  |
Other long-term investments | $ 1,622.7 | $ 1,377.8 |  |
Kudu investments |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Other long-term investments | $ 813.2 | $ 669.5 |  |
Kudu investments | Minimum |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Ownership interest (as a percent) | 4.10% | 3.20% |  |
Kudu investments | Maximum |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Ownership interest (as a percent) | 33.00% | 32.00% |  |
Marketing Technology (MediaAlpha) |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Ownership interest (as a percent) | 27.40% | 28.00% |  |
Other long-term investments | $ 148.2 | $ 261.6 |  |
PassportCard/DavidShield |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Ownership interest (as a percent) | 53.80% | 53.80% | 53.80% | 50.00%
Other long-term investments | $ 132.0 | $ 120.0 |  |
Elementum Holdings, L.P. |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Ownership interest (as a percent) | 29.70% | 29.70% |  |
Other long-term investments | $ 45.0 | $ 45.0 |  |
Other |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Other long-term investments | 102.7 | 109.3 |  |
Equity Method Investments |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Other long-term investments | $ 27.7 | $ 17.8 |  |

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