Income Taxes - (Benefit) Provision for Income Taxes Differs from Amounts Computed by Applying Statutory Federal Corporate Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
(Benefit) provision for income taxes at statutory rate	$ (518)	$ (10,712)	$ 34	$ (13,643)
Tax effect of:
Tax-exempt investment income		(10)		(20)
Stock option expirations		13	229	17
State income taxes, net of federal income tax benefit and state valuation allowance	(63)	(65)	6	(6)
Other	4	66		75
Income tax expense (benefit)	$ (577)	$ (10,708)	$ 269	$ (13,577)