Underwriting Information - Gross Written Premiums by State (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%
California
Gross written premiums
Amount	$ 32,751	$ 30,449
% of GWP	45.80%	56.40%
Texas
Gross written premiums
Amount	$ 15,791	$ 10,439
% of GWP	22.10%	19.30%
Hawaii
Gross written premiums
Amount	$ 3,052	$ 2,091
% of GWP	4.30%	3.90%
Washington
Gross written premiums
Amount	$ 2,606	$ 1,594
% of GWP	3.60%	3.00%
South Carolina
Gross written premiums
Amount	$ 2,410	$ 1,669
% of GWP	3.40%	3.10%
Oregon
Gross written premiums
Amount	$ 2,097	$ 1,456
% of GWP	2.90%	2.70%
North Carolina
Gross written premiums
Amount	$ 1,684	$ 740
% of GWP	2.40%	1.40%
Alabama
Gross written premiums
Amount	$ 1,529	$ 1,010
% of GWP	2.10%	1.90%
Other
Gross written premiums
Amount	$ 9,574	$ 4,583
% of GWP	13.40%	8.30%