Reinsurance - Effects of reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Premiums written
Direct	$ 104,372	$ 80,798
Assumed	130,530	105,891
Ceded	(48,202)	(41,302)
Net	186,700	145,387
Premiums earned
Direct	88,536	63,517
Assumed	99,529	113,481
Ceded	(48,026)	(30,904)
Net premiums earned	140,039	146,094
Losses and loss adjustment expenses
Direct	88,694	48,404
Assumed	74,720	84,524
Ceded	(52,738)	(22,078)
Net	$ 110,676	$ 110,850