Tax Effects of Temporary Differences That Give Rise to Federal, Foreign, State and Local Deferred Tax Assets and Deferred Tax Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Loss reserve discount	$ 27,822	$ 29,687
Unearned premiums	25,706	22,860
Compensation related	6,782	5,285
State and local net deferred tax assets	555	499
Other	3,889	4,245
Total gross deferred tax assets	64,754	62,576
Less: Valuation allowance	(555)	(499)
Total deferred tax assets	64,199	62,077
Deferred tax liabilities:
Deferred acquisition costs	(19,258)	(16,903)
Net unrealized gains on securities	(12,635)	(36,200)
Other	(4,119)	(5,758)
Total deferred tax liabilities	(36,012)	(58,861)
Net deferred income tax asset (liability)	$ 28,187	$ 3,216