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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Premiums written:
Direct	$ 646,278	$ 598,783
Assumed	6,320	6,081
Ceded premiums written	(87,239)	(86,776)
Net	565,359	518,088
Premiums earned:
Direct	606,661	562,042
Assumed	6,270	5,908
Ceded premiums earned	(90,473)	(91,827)
Net	522,458	476,123
Loss and loss expense incurred:
Direct	361,639	312,246
Assumed	6,355	4,662
Ceded loss and loss expense incurred	(70,850)	(31,909)
Net	297,144	284,999
National Flood Insurance Program [Member]
Premiums written:
Ceded premiums written	(53,248)	(53,842)
Premiums earned:
Ceded premiums earned	(56,814)	(58,998)
Loss and loss expense incurred:
Ceded loss and loss expense incurred	$ (40,718)	$ (6,249)

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