Investments - Summary of Fixed Maturities and Equity Securities with Unrealized Losses (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 99,989	$ 207,175
Less Than 12 Months, Unrealized Losses	463	1,898
More Than 12 Months, Fair Value	21,640	43,913
More Than 12 Months, Unrealized Losses	199	488
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	15,647	50,803
Less Than 12 Months, Unrealized Losses	76	822
More Than 12 Months, Fair Value	4,973	4,642
More Than 12 Months, Unrealized Losses	30	104
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,588	65,171
Less Than 12 Months, Unrealized Losses	5	363
More Than 12 Months, Fair Value		13,405
More Than 12 Months, Unrealized Losses		99
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	40,874	16,694
Less Than 12 Months, Unrealized Losses	172	84
More Than 12 Months, Fair Value	3,259	6,852
More Than 12 Months, Unrealized Losses	34	72
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	40,344	72,878
Less Than 12 Months, Unrealized Losses	164	536
More Than 12 Months, Fair Value	13,408	19,014
More Than 12 Months, Unrealized Losses	135	213
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,536	1,629
Less Than 12 Months, Unrealized Losses	46	93
More Than 12 Months, Fair Value
More Than 12 Months, Unrealized Losses