Losses and Loss Adjustment Expenses Incurred and Paid - Information Regarding the Reserve for Unpaid Losses and LAE (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance [Abstract]
Liability for unpaid losses and LAE at beginning of year, gross			$ 84,286	$ 79,260	$ 69,436
Reinsurance balances receivable, beginning balance			(305)	(260)	(187)
Liability for unpaid losses and LAE at beginning of year, net			83,981	79,000	69,249
Add: Provision for losses and LAE:
Current year			166,185	145,877	144,207
Prior years			(4,883)	(3,038)	4,016
Net losses and LAE incurred			161,302	142,839	148,223
Less: Losses and LAE paid:
Current year			98,442	88,726	89,157
Prior years	2,600	2,600	50,590	49,132	49,315
Net losses and LAE paid			149,032	137,858	138,472
Liability for unpaid losses and LAE at end of year, net	96,251	83,981	96,251	83,981	79,000
Reinsurance balances receivable, ending balance	362	305	362	305	260
Liability for unpaid losses and LAE at end of year, gross	$ 96,613	$ 84,286	$ 96,613	$ 84,286	$ 79,260