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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Premiums written:
Direct	$ 557,891	$ 528,816
Assumed	7,850	8,482
Ceded premiums written	(88,991)	(87,174)
Net	476,750	450,124
Premiums earned:
Direct	536,700	494,066
Assumed	10,185	12,463
Ceded premiums earned	(90,390)	(85,589)
Net	456,495	420,940
Loss and loss expense incurred:
Direct	358,349	365,646
Assumed	7,479	9,074
Ceded loss and loss expense incurred	(45,282)	(104,871)
Net	$ 320,546	$ 269,849
Number of insurance subsidiaries	10
Percentage of NFIP claims ceded by federal government	100.00%

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