Fair Value Measurements - Summary of Carrying Values and Corresponding Fair Values for Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value Of Financial Instruments [Line Items]
Fixed maturity securities-held to maturity	$ 561,179	$ 627,349
Fixed maturity securities-held-to-maturity	536,583	583,287
Fixed maturity securities-available for sale	237,877	149,139
Equity securities	9,302	6,766
Carrying Amount [Member]
Fair Value Of Financial Instruments [Line Items]
Fixed maturity securities-held-to-maturity	536,583	583,287
Fixed maturity securities-available for sale	237,877	149,139
Equity securities	9,302	6,766
Cash and cash equivalents	123,077	92,676
Short-term investments	84,422	68,924
Other investments	10,591
Fair Value [Member]
Fair Value Of Financial Instruments [Line Items]
Fixed maturity securities-held to maturity	561,179	627,349
Fixed maturity securities-available for sale	237,877	149,139
Equity securities	9,302	6,766
Cash and cash equivalents	123,077	92,676
Short-term investments	84,422	68,924
Other investments	$ 10,591