Income Taxes - Provision (Benefit) for Income Taxes Differs from Amounts Computed by Applying Statutory Federal Corporate Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes at statutory rate	$ 733	$ 1,182	$ 2,264	$ (3,227)
Tax effect of:
Tax-exempt investment income	(10)	(10)	(21)	(13)
Change in the beginning of the period balance of the valuation allowance for deferred tax assets allocated to federal income taxes	(716)	(3,693)	(2,352)	678
Stock-based compensation	22	2,516	193	2,530
State income taxes, net of federal income tax benefit and valuation allowance	129	99	343	(84)
Other	6	5	18	32
Income tax expense (benefit)	$ 164	$ 99	$ 445	$ (84)