Reinsurance - Effects of reinsurance on premiums written and earned and on net loss and LAE (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reinsurance Disclosures [Abstract]
Direct premiums written	$ 5,193	$ 3,778
Assumed premiums written	6,541	(564,917)
Ceded premiums written	(1,362)	(391)
Premiums written, net	10,372	(561,530)
Direct premiums earned	4,761	3,024
Assumed premiums earned	27,453	180,788
Ceded premiums earned	(999)	(710)
Net premiums earned	31,215	183,102
Gross loss and LAE	20,994	152,734
Loss and LAE ceded	92	(45)
Net loss and loss adjustment expenses	$ 21,086	$ 152,689