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Business Concentration (Details) | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Net Premiums Written |  |  |
Concentration Risk [Line Items] |  |  |
Concentration percentage | 5.40% | 10.30% | 23.60%
NORTH CAROLINA | Geographic Concentration Risk |  |  |
Concentration Risk [Line Items] |  |  |
Concentration percentage | 35.50% | 32.80% | 28.40%
TEXAS | Geographic Concentration Risk |  |  |
Concentration Risk [Line Items] |  |  |
Concentration percentage | 20.50% | 22.40% | 36.50%
SOUTH CAROLINA | Geographic Concentration Risk |  |  |
Concentration Risk [Line Items] |  |  |
Concentration percentage | 10.00% | 10.10% | 7.70%

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