Reinsurance (Ceded Premiums and Losses Related to Flood Operations) (Details) - National Flood Insurance Program [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Percentage of NFIP claims ceded by federal government			100.00%
Ceded premiums written	$ (77,318)	$ (74,863)	$ (213,592)	$ (206,451)
Ceded premiums earned	(68,427)	(65,846)	(202,656)	(191,914)
Ceded loss and loss expenses incurred	$ (48,132)	$ (27,459)	$ (66,219)	$ (62,208)