Reinsurance - Impact of Catastrophe Excess of Loss Reinsurance and Quota Share Treaties on Premiums Written and Earned (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Premiums Written:
Direct	$ 86,257	$ 78,140	$ 307,199	$ 281,912
Assumed	(172)	(221)	(1,255)	(2,297)
Gross written	86,085	77,919	305,944	279,615
Gross written	86,085	77,919	305,944	279,615
Ceded	(27,684)	(28,310)	(83,764)	(74,923)
Net premiums written	58,401	49,609	222,180	204,692
Premiums Earned:
Direct	85,357	75,512	245,638	193,465
Assumed	3,587	5,732	28,415	52,278
Gross earned	88,944	81,244	274,053	245,743
Ceded	(27,684)	(28,310)	(83,764)	(74,923)
Net premiums earned	$ 61,260	$ 52,934	$ 190,289	$ 170,820