Reinsurance Reinsurance (Details) - USD ($)		12 Months Ended
	Jun. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Insurance [Abstract]
Reinsurance Retention Policy, Excess Retention, Amount Reinsured	$ 3,100,000,000
Insurance Commissions and Fees, Flood Program		$ 1,575,000	$ 1,255,000	$ 1,056,000
Percentage of Flood Premiums Ceded		100.00%
Increase (Decrease) in Ceded Losses and LAE Incurred		$ (230,954,000)
Losses ceded under aggregate contract		$ 20,000,000