Investments - Fair Value and Gross Unrealized Losses of Fixed Maturity Securities in Continuous Unrealized Loss Position for Greater than 12 Months (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013 Security	Dec. 31, 2012 Security
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	2	1
Fair Value	$ 947	$ 212
Gross Unrealized Losses	(17)	(78)
Less Than or Equal to 10% [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	2
Fair Value	947
Gross Unrealized Losses	(17)
Greater Than 10% [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities		1
Fair Value		212
Gross Unrealized Losses		$ (78)