Reinsurance - Impact of Catastrophe Excess of Loss Reinsurance Treaties on Premiums Written and Earned (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Premiums Written:
Direct	$ 79,662	$ 70,849
Assumed	(723)	(1,600)
Gross written	78,939	69,249
Ceded	(27,508)	(21,996)
Net premiums written	51,431	47,253
Premiums Earned:
Direct	78,520	53,127
Assumed	15,368	29,420
Gross earned	93,888	82,547
Ceded	(27,508)	(21,996)
Net premiums earned	$ 66,380	$ 60,551