Basis of Presentation and Significant Accouting Policies (Basis of Presentation) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Apr. 04, 2019	Apr. 03, 2019	Jan. 01, 2019	Dec. 31, 2018	May 11, 2018	Jul. 31, 2012
Basis of Presentation
ROU lease asset	$ 23.8
Operating lease liability	$ 24.1
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%
Fully diluted ownership interest (as a percent)		85.40%	42.70%		42.70%
Unfunded Capital Commitment	$ 105.0		$ 250.0
Accounting Standards Update 2016-02
Basis of Presentation
ROU lease asset	23.8			$ 23.2
Operating lease liability	$ 24.1			$ 23.2