Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized gains (losses) on investments	$ 3,950	$ (1)	$ 4,852	$ (1)
Income taxes, current	(1,524)		(1,872)
Net of tax	2,426		2,980
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	3,950	(1)	4,852	(1)
Income taxes, current	(1,524)		(1,872)
Net of tax	$ 2,426		$ 2,980