Income Taxes - Provision (Benefit) for Income Taxes Differs from Amounts Computed by Applying Statutory Federal Corporate Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes at statutory rate	$ (900)	$ 3,403	$ 3,440
Tax effect of:
Tax-exempt investment income	(22)	(21)	(27)
Change in the beginning of the period balance of the valuation allowance for deferred tax assets allocated to federal income taxes	9	(22,427)	(4,277)
Stock-based compensation	22	137	1,133
State income taxes, net of federal income tax benefit and state valuation allowance	142	525	479
Permanent items	107	38	(98)
Income tax expense (benefit)	$ (642)	$ (18,345)	$ 650