Investments - Summary of Fixed Maturities and Equity Securities with Unrealized Losses (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 90,874	$ 207,175
Less Than 12 Months, Unrealized Losses	1,026	1,898
More Than 12 Months, Fair Value	15,789	43,913
More Than 12 Months, Unrealized Losses	301	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	15,007	50,803
Less Than 12 Months, Unrealized Losses	60	822
More Than 12 Months, Fair Value	2,254	4,642
More Than 12 Months, Unrealized Losses	10	104
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	8,119	65,171
Less Than 12 Months, Unrealized Losses	42	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	25,323	16,694
Less Than 12 Months, Unrealized Losses	268	84
More Than 12 Months, Fair Value		6,852
More Than 12 Months, Unrealized Losses		72
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	34,106	72,878
Less Than 12 Months, Unrealized Losses	210	536
More Than 12 Months, Fair Value	13,535	19,014
More Than 12 Months, Unrealized Losses	291	213
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	8,319	1,629
Less Than 12 Months, Unrealized Losses	446	93
More Than 12 Months, Fair Value
More Than 12 Months, Unrealized Losses