Schedule VI. Supplemental Information Concerning Property-Casualty Insurance Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Supplemental Information For Property Casualty Insurance Underwriters [Abstract]
Deferred Policy Acquisition Cost	$ 19,171	$ 18,419	$ 16,578
Reserves for Unpaid Loss and Loss Adjustment Expense	614,557	570,450	538,214
Unearned Premium	164,296	140,528	118,699
Earned Premium	329,983	290,689	251,015
Net Investment Income	27,029	27,018	26,340
Loss and LAE Related to Current Period	241,584	222,393	196,269
Loss and LAE Related to Prior Periods	(12,611)	(2,490)	(6,563)	(3,100)	(3,900)	(2,300)
Amortization of Deferred Policy Acquisition Costs	(40,526)	(39,120)	(34,623)
Paid Claims and Claim Adjustment Expenses	178,375	181,920	179,097
Net Premiums Written	$ 353,752	$ 312,518	$ 258,220