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Equity Method Eligible Investments - Carrying Value and Ownership Percentages (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | May 07, 2020 | May 06, 2020 | May 31, 2019
--- | --- | --- | --- | --- | ---
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Other long-term investments | $ 1,377.8 | $ 786.8 |  |  |
Equity Method Investments |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Other long-term investments | 17.8 | 15.2 |  |  |
Kudu's Participation Contracts |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Other long-term investments | $ 669.5 | $ 400.6 |  |  |
Kudu's Participation Contracts | Minimum |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Ownership interest (as a percent) | 3.20% | 3.20% |  |  |
Kudu's Participation Contracts | Maximum |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Ownership interest (as a percent) | 32.00% | 35.00% |  |  |
MediaAlpha |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Ownership interest (as a percent) | 28.00% | 35.00% |  |  |
Other long-term investments | $ 261.6 | $ 802.2 |  |  |
PassportCard/DavidShield |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Ownership interest (as a percent) | 53.80% | 53.80% | 53.80% | 50.00% |
Other long-term investments | $ 120.0 | $ 95.0 |  |  |
Elementum Holdings, L.P. |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Ownership interest (as a percent) | 29.70% | 28.90% |  |  | 30.00%
Other long-term investments | $ 45.0 | $ 55.1 |  |  |
Other Investment Sector |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Other long-term investments | $ 109.3 | $ 132.2 |  |  |

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