Statutory Accounting Practices Disclosure - Net Income (Details) - USD ($) $ in Thousands	3 Months Ended								4 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Apr. 29, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statutory Accounting Practices [Line Items]
Net Income (Loss) Attributable to Parent	$ 27,001	$ (28,012)	$ 7,257	$ 3,899	$ (10,517)	$ 3,423	$ 9,841	$ 2,951		$ 10,145	$ 5,698	$ 27,358
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Commissions										401	17,486	339
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Deferred Income Taxes										9,413	(3,255)	(2,518)
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Deferred Policy Acquisition Costs										(17,935)	(6,342)	(4,962)
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Allowance for Doubtful Accounts										240	(24)	97
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Prepaid Expenses										101	(538)	131
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Premium Deficiency Reserve										(1,800)	0	0
Statutory Accounting Practices, GAAP to Statutory, Increase (Decrease) Due to Investments										1,148
Statutory Accounting Practices, GAAP to Statutory, Increase (Decrease) Due to Other, net										(71)	166	0
Statutory Accounting Practices, GAAP TO Statutory, Increase (Decrease) Due to Operations of Non-Statutory Subsidiaries										(6,930)	(10,621)	(10,077)
Statutory Accounting Practices, Statutory Net Income Amount										832	6,083	10,520
Family Security Holdings (FSH)
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Net Income Amount												$ 152
Interboro Insurance Company
Statutory Accounting Practices [Line Items]
Net Income (Loss) Attributable to Parent									$ 8,187
Statutory Accounting Practices, Statutory Net Income Amount											$ 3,513
American Coastal Insurance Company
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Net Income Amount										$ 6,120