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Basis of Presentation and Significant Accounting Policies - Reportable Segments (Details) - USD ($) $ in Millions |  | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jan. 01, 2021 | Dec. 31, 2021 | Dec. 31, 2020 | Apr. 04, 2019 | Apr. 03, 2019 | Feb. 05, 2018 | Dec. 31, 2012
Ark |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Percent of shares outstanding | 12.50% | 12.50% |  |  |  |  |
HG Global |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Percentage of par value of policy reinsured |  | 15.00% |  |  |  |  |
Surplus notes |  |  |  |  |  |  | $ 503.0
Ark | Ark |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Ownership interest (as a percent) |  | 72.00% |  |  |  |  |
Fully diluted ownership interest (as a percent) |  | 63.00% |  |  |  |  |
Preferred stocks | HG Global |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Ownership interest (as a percent) |  | 96.90% | 96.90% |  |  |  |
Common equity securities | HG Global |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Ownership interest (as a percent) |  | 88.40% | 88.40% |  |  |  |
NSM |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Ownership interest (as a percent) |  | 96.50% | 96.60% |  |  |  |
Fully diluted ownership interest (as a percent) |  | 87.30% | 89.60% |  |  |  |
Kudu |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |
Ownership interest (as a percent) |  | 99.30% | 99.30% | 99.10% | 49.50% | 49.50% |
Fully diluted ownership interest (as a percent) |  | 84.70% | 85.40% | 85.40% | 42.70% | 42.70% |

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