Schedule VI - Supplemental Information Concerning Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Claim and claim adjustment expenses incurred related to current year	$ 174,795	$ 113,819	$ 79,932
Claim and claim adjustment expenses incurred related to prior year	12,546	(9,466)	1,104
Property and Casualty Insurance [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred acquisition costs	38,962	15,547	13,610
Loss and loss adjustment expense reserves	158,110	97,340	78,330
Unearned premiums	294,022	253,960	192,424
Earned premiums	259,872	210,020	170,905
Net investment income	9,063	7,226	5,385
Claim and claim adjustment expenses incurred related to current year	174,795	113,819	79,932
Claim and claim adjustment expenses incurred related to prior year	12,546	(9,466)	1,104
Amortization of deferred acquisition costs	75,850	37,276	27,474
Paid claims and claims adjustment expense	160,154	82,445	71,803
Premiums written	$ 319,499	$ 225,254	$ 175,158