Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive Income (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
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized gains (losses) on investments	$ 501	$ 56	$ 5,353	$ 55
Income taxes, current	(193)	(22)	(2,065)	(21)
Net of tax	308	34	3,288	34
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized gains (losses) on investments	501	56	5,353	55
Income taxes, current	(193)	(22)	(2,065)	(21)
Net of tax	$ 308	$ 34	$ 3,288	$ 34