Investments - Progression of Credit-Related Portion of OTTI on Investments (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
Investments Debt And Equity Securities [Abstract]
Beginning balance	$ (2,632)	$ (2,607)	$ (2,632)	$ (2,666)
Additional credit impairments on:
Previously impaired securities	0		0	(28)
Securities without previous impairments	0		0
Total additional credit impairments securities	0		0	(28)
Reductions for securities sold (realized)	0	(8)	0	(95)
Ending balance	$ (2,632)	$ (2,599)	$ (2,632)	$ (2,599)