Investments - Summary of Contractual Maturities of Company's Fixed Maturity and Short-Term Investments Classified as Available-for-Sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	$ 29,022	$ 45,295
Due after one year through five years, Amortized Cost	147,873	141,400
Due after five years through ten years, Amortized Cost	2,935	69
Due after ten years, Amortized cost	2,766	2,671
Amortized cost due in years, Total	182,596	189,435
Total amortized cost	238,617	243,302
Due in one year or less, Fair Value	29,325	45,596
Due after one year through five years, Fair Value	149,441	143,445
Due after five years through ten years, Fair Value	2,912	70
Due after ten years, Fair Value	3,519	3,428
Total fair value or available for sale debt securities due in years	185,197	192,539
Total fair value	241,309	246,364
Due in one year or less, Percentage of Total Fair Value	12.10%	18.50%
Due after one year through five years, Percentage of Total Fair Value	61.90%	58.20%
Due after five years through ten years, Percentage of Total Fair Value	1.20%	0.10%
Due after ten years, Percentage of Total Fair Value	1.50%	1.40%
Percentage of Total Fair Value	76.70%	78.20%
Percentage of Total Fair Value	100.00%	100.00%
Residential Mortgage-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	4,454	17,523
Total fair value	4,548	17,507
Percentage of Total Fair Value	1.90%	7.10%
Asset-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	51,567	36,344
Total fair value	$ 51,564	$ 36,318
Percentage of Total Fair Value	21.40%	14.70%