Reinsurance Agreements (Details) (USD $)	9 Months Ended
	Sep. 30, 2013 Structure	Sep. 30, 2012	Dec. 31, 2012
Reinsurance Agreements [Abstract]
Number of types of reinsurance structures	3
Liability for Catastrophe Claims [Line Items]
Prepaid reinsurance premiums	$ 1,707,000		$ 7,045,000
Increase in total insured value	8,600,000,000	2,100,000,000
Percentage increase in total insured value (in hundredths)	25.40%	12.60%
Increase reinsurance premiums for total insured value	7,900,000	2,400,000
Percentage increase in reinsurance premiums for total insured value (in hundredths)	13.30%	3.00%
Trust agreement for loss exposure	4,800,000		4,800,000
2012-2013 Hurricane Season [Member]
Liability for Catastrophe Claims [Line Items]
Aggregate catastrophic loss coverage	328,300,000
Maximum single event coverage	246,500,000
Amount retained per Loss	8,000,000
Coverage afforded by FHCF	144,700,000
Percentage of FHCF coverage to total coverage (in hundredths)	44.10%
Reinsurance premium	9,600,000
Prepaid reinsurance premiums	41,600,000
2013-2014 Hurricane Season [Member]
Liability for Catastrophe Claims [Line Items]
Aggregate catastrophic loss coverage	558,300,000
Maximum single event coverage	416,000,000
Amount retained per Loss	7,000,000
Coverage afforded by FHCF	273,700,000
Percentage of FHCF coverage to total coverage (in hundredths)	49.00%
Reinsurance premium	21,400,000
Prepaid reinsurance premiums	$ 67,600,000