Underwriting Information - Gross Written Premiums by Product (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Gross written premiums
Amount	$ 71,494	$ 54,031
% of GWP	100.00%	100.00%
Residential Earthquake
Gross written premiums
Amount	$ 28,756	$ 29,308
% of GWP	40.20%	54.30%
Commercial All Risk
Gross written premiums
Amount	$ 12,456	$ 7,565
% of GWP	17.40%	14.00%
Commercial Earthquake
Gross written premiums
Amount	$ 10,848	$ 6,532
% of GWP	15.20%	12.10%
Specialty Homeowners
Gross written premiums
Amount	$ 9,845	$ 7,780
% of GWP	13.80%	14.40%
Hawaii Hurricane
Gross written premiums
Amount	$ 2,695	$ 2,074
% of GWP	3.80%	3.80%
Residential Flood
Gross written premiums
Amount	$ 1,526	$ 772
% of GWP	2.10%	1.40%
Other
Gross written premiums
Amount	$ 5,368
% of GWP	7.50%