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	Dec. 31, 2012 Security
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	1
Fair Value	$ 212
Gross Unrealized Losses	(78)
Less Than or Equal to 10% [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities
Fair Value
Gross Unrealized Losses
Greater Than 10% [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	1
Fair Value	212
Gross Unrealized Losses	$ (78)