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Basis of Presentation and Significant Accouting Policies (Basis of Presentation) (Details) - USD ($) $ in Millions | Sep. 30, 2019 | Apr. 04, 2019 | Apr. 03, 2019 | Mar. 31, 2019 | Jan. 01, 2019 | Dec. 31, 2018 | May 11, 2018 | Jul. 31, 2012
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Basis of Presentation |  |  |  |  |  |  |  |
Ownership interest (as a percent) | 50.00% |  |  |  |  | 50.00% |  |
ROU lease asset | $ 23.0 |  |  |  |  |  |  |
Operating lease liability | $ 23.3 |  |  |  |  |  |  |
HG Global |  |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |  |
Percentage of par value of policy reinsured | 15.00% |  |  |  |  |  |  |
Surplus notes | $ 481.3 |  |  |  |  |  |  | $ 503.0
Preferred Stock | HG Global |  |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |  |
Ownership interest (as a percent) | 96.90% |  |  |  |  | 96.90% |  |
Common Stock | HG Global |  |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |  |
Ownership interest (as a percent) | 88.40% |  |  |  |  | 88.40% |  |
NSM Insurance HoldCo, LLC |  |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |  |
Ownership interest (as a percent) | 96.40% |  |  |  |  | 95.50% | 95.00% |
Fully diluted ownership interest (as a percent) | 88.40% |  |  |  |  | 85.00% |  |
Kudu Investment Management, LLC |  |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |  |
Ownership interest (as a percent) |  | 99.10% | 49.50% | 49.50% |  | 49.50% |  |
Fully diluted ownership interest (as a percent) |  | 85.40% | 42.70% | 42.70% |  | 42.70% |  |
Accounting Standards Update 2016-02 |  |  |  |  |  |  |  |
Basis of Presentation |  |  |  |  |  |  |  |
ROU lease asset | $ 23.0 |  |  |  | $ 23.2 |  |  |
Operating lease liability | $ 23.3 |  |  |  | $ 23.2 |  |  |

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