Deferred Policy Acquisition Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	$ 18,652	$ 14,123	$ 14,801	$ 11,775
Policy acquisition costs deferred:
Direct commissions deferred	14,358	10,232	40,601	29,907
Ceding commissions deferred	(2,824)	(3,123)	(9,338)	(8,273)
Other underwriting and policy acquisition costs	989	781	2,803	2,284
Policy acquisition costs deferred	12,523	7,890	34,066	23,918
Amortization of net policy acquisition costs	(10,115)	(7,528)	(27,807)	(21,208)
Balance, end of period	$ 21,060	$ 14,485	$ 21,060	$ 14,485