Aggregate dividends declared during the period for each share of common stock outstanding.

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Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended						9 Months Ended
	Nov. 06, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Subsequent Event
Proceeds from Contributions from Parent								$ 25,000
Dividends declared per share (in usd per share)		$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.18	$ 0.18
Subsequent Event
Subsequent Event
Dividends declared per share (in usd per share)	$ 0.06
American Coastal Insurance Company
Subsequent Event
Statutory Accounting Practices, Dividends Paid with Approval of Regulatory Agency								$ 50,000
Interboro Insurance Company
Subsequent Event
Statutory Accounting Practices, Dividends Paid with Approval of Regulatory Agency								1,764
Minimum
Subsequent Event
Loss Contingency, Estimate of Possible Loss		$ 25,000						25,000
Maximum
Subsequent Event
Loss Contingency, Estimate of Possible Loss		$ 35,000						$ 35,000