Investments - Credit Ratings Company's Fixed Maturity and Short-term Investments Available-for-Sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 238,617	$ 243,302
Fair Value	241,309	246,364
Percentage of Total Fair Value	100.00%	100.00%
AAA [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	138,462	125,729
Fair Value	139,369	127,433
Percentage of Total Fair Value	57.80%	51.70%
AA [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	53,404	74,692
Fair Value	53,980	75,181
Percentage of Total Fair Value	22.40%	30.50%
A [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	36,834	33,834
Fair Value	37,683	34,607
Percentage of Total Fair Value	15.60%	14.10%
BBB or Lower [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,917	8,957
Fair Value	10,277	8,963
Percentage of Total Fair Value	4.20%	3.60%
Not Rated [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		90
Fair Value		$ 180
Percentage of Total Fair Value		0.10%