Unpaid Losses and Loss Adjustment Expenses - Changes in the Liability for Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves - beginning of period	$ 87,896	$ 54,651
Less: reinsurance recoverables on unpaid losses	20,066	6,658
Net reserves - beginning of period	67,830	47,993
Add: incurred losses and LAE, net of reinsurance:
Current period	13,344	12,654
Prior period	(16)	3,079
Total net incurred losses and LAE	13,328	15,733
Deduct: loss and LAE payments, net of reinsurance:
Current period	1,588	1,903
Prior period	12,711	8,813
Total net loss and LAE payments	14,299	10,716
Net reserves - end of period	66,859	53,010
Plus: reinsurance recoverables on unpaid losses	20,063	9,125
Less: deferred gain on ADC	(1,431)	0
Gross reserves - end of period	$ 85,491	$ 62,135