Liability for Unpaid Losses and Loss Adjustment Expense Liability for Unpaid Losses and Loss Adjustment Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Current Year Claims and Claims Adjustment Expense	$ 281,365	$ 185,476	$ 122,114
Prior Year Claims and Claims Adjustment Expense	16,988	(2,368)	(4,037)
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	298,353	183,108	118,077
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year	210,970	127,306	83,967
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years	62,506	36,698	26,420
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid	273,476	164,004	110,387
Liability for Unpaid Claims and Claims Adjustment Expense, Net	122,131	74,678	53,184
Reinsurance Recoverable on Unpaid Losses and LAE	18,724	2,114	1,252	$ 1,957
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Including Acquisition		97,254	55,574	45,494
Unpaid losses and loss adjustment expenses	140,855	76,792	54,436	47,451
Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount	83,447	45,502	29,726
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount	$ 57,408	31,290	24,710
Family Security Holdings (FSH)
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments		0	2,390	0
Interboro Insurance Company
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments		$ 22,576	$ 0	$ 0