Underwriting, Acquisition and Insurance Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Underwriting, Acquisition and Insurance Expenses [Abstract]
Gross commissions	$ 9,517	$ 8,001	$ 26,652	$ 22,694
Ceding commissions	(2,716)	(2,479)	(7,624)	(7,291)
Other operating expenses	7,049	5,467	19,739	17,372
Underwriting, acquisition, and insurance expenses	13,850	10,989	38,767	32,775
Salaries, bonuses and employee benefits	$ 5,300	$ 4,200	$ 15,600	$ 13,700