Reinsurance - Effects of Reinsurance Premium Written and Earned (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Insurance [Abstract]
Direct Written	$ 262,110	$ 247,498	$ 200,983
Assumed Written	37,381	35,500	29,311
Ceded Written	(450)	(372)	(265)
Written Total	299,041	282,626	230,029
Direct Earned	265,256	233,652	191,093
Assumed Earned	38,522	33,707	27,487
Ceded Earned	(450)	(372)	(265)
Earned Total	$ 303,328	$ 266,987	$ 218,315