Reinsurance - Effects of reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Premiums written
Direct	$ 100,469	$ 85,656	$ 204,841	$ 166,454
Assumed	57,458	76,322	187,988	182,213
Ceded	(52,071)	(42,608)	(100,273)	(83,910)
Net	105,856	119,370	292,556	264,757
Premiums earned
Direct	89,553	70,445	178,089	133,962
Assumed	90,447	115,622	189,976	229,103
Ceded	(48,465)	(34,749)	(96,491)	(65,653)
Net premiums earned	131,535	151,318	271,574	297,412
Losses and loss adjustment expenses
Direct	82,291	62,976	170,985	111,380
Assumed	70,337	88,651	145,057	173,175
Ceded	(47,842)	(40,211)	(100,580)	(62,289)
Net	$ 104,786	$ 111,416	$ 215,462	$ 222,266