Reinsurance Reinsurance - Narrative (Details) (USD $)	0 Months Ended	12 Months Ended			0 Months Ended
	Jun. 01, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 02, 2015
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
ISO Catastrophe Definition		$ 25,000,000
Reinsurance Retention Policy, Excess Retention, Amount Reinsured	1,105,200,000
Prepaid Reinsurance Premiums		63,827,000	55,268,000
Policyholder Benefits and Claims Incurred, Assumed and Ceded		2,667,000	2,521,000
Percentage of Flood Premiums Ceded		100.00%
Insurance Commissions and Fees, Flood Program		1,078,000	570,000	267,000
Increase (Decrease) in Ceded Losses and LAE Incurred		521,000
Maximum [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Excess Retention, Amount Reinsured	1,080,200,000
Unaffiliated Private Reinsurers [Member] | Maximum [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Aggregate Coverage for Covered Losses Under Reinsurance Contract	525,000,000
First Catastrophic Event [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Coverage, Percentage Placed	100.00%
Second Catastrophic Event [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Excess Retention, Amount Reinsured	15,000,000
Reinsurance Coverage, Percentage Placed	100.00%
Catastrophe [Member] | Florida Hurricane Catastrophe Fund [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance, Aggregate Value of Property Covered Under Contracts	555,200,000
Reinsurance, Losses Not Covered Prior to Coverage Beginning	230,800,000
Prepaid Reinsurance Premiums	38,594,000
Catastrophe [Member] | First Catastrophic Event [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Amount Retained	25,000,000
Catastrophe [Member] | Second Catastrophic Event [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Amount Retained	10,000,000
Catastrophe [Member] | Second Catastrophic Event [Member] | Unaffiliated Private Reinsurers [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Amount Retained	15,000,000
Prepaid Reinsurance Premiums	90,600,000
Subsequent Event [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Excess Retention, Amount Reinsured					3,000,000
Reinsurance Retention Policy, Amount Retained					1,000,000
Subsequent Event [Member] | Catastrophe [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Retention Policy, Excess Retention, Amount Reinsured					$ 25,000,000