Reserve for Unpaid Losses - Additional Information (Detail) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2014
Insurance [Abstract]
Losses incurred related to the prior year redundancy	$ 2,500,000		$ 385,000	$ 136,000
Favorable development of losses and LAE reserve		$ 4,500,000