Reconciliation of Difference Between Company's Income Tax Benefit (Provision) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Income tax benefit at statutory federal tax rate of 34%	$ 2,845	$ 4,711
State taxes, net of federal benefit	(22)	(17)
Foreign taxes provisions provided for at rates other than U.S statutory rate	(687)	(424)
Federal rate adjustment	(15,780)
Change in valuation allowance	13,931	(4,064)
Permanent differences	200
Other	(273)	(338)
Total benefit (provision) for income taxes	$ 214	$ (132)