Supplementary Information for Property Casualty Underwriters (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs	$ 25,238	$ 22,177	$ 18,265
Reserves for Unpaid Claims and Claim Adjustment Expenses	675,472	779,466	879,114
Discount If Any Deducted	4,000	6,000	8,000
Unearned Premiums	120,815	116,629	94,114
Earned Premiums	268,519	248,722	238,862
Net Investment Income	28,821	37,209	47,557
Claims and Claim Adjustment Expense Incurred Related To Current Year	153,994	140,873	149,183
Claims and Claim Adjustment Expense Incurred Related To Prior Year	(16,433)	(7,882)	4,445
Amortization Of Deferred Policy Acquisition Costs	57,051	53,787	48,852
Paid Claims and Claim Adjustment Expenses	172,265	184,564	202,786
Premiums Written	$ 273,181	$ 271,984	$ 219,547