Income Taxes - Provision (Benefit) for Income Taxes Differs from Amounts Computed by Applying Statutory Federal Corporate Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Benefit for income taxes at statutory rate	$ (115)	$ (1,584)	$ (13,758)	$ (1,061)
Tax effect of:
Tax-exempt investment income	(10)	(5)	(30)	(15)
Change in the beginning of the period balance of the valuation allowance for deferred tax assets allocated to federal income taxes	(6)	6	51	8
Stock-based compensation	12		29	22
State income taxes, net of federal income tax benefit and state valuation allowance	116	(24)	110	134
Other	9	101	27	99
Income tax expense (benefit)	$ 6	$ (1,506)	$ (13,571)	$ (813)