Company's Deferred Tax Assets, Net of Deferred Tax Liabilities and Valuation Allowance (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred tax assets, net of deferred tax liabilities	$ 18,773	$ 12,242
Valuation allowance	(944)	(832)
Deferred tax assets, net of deferred tax liabilities and valuation allowance	$ 17,829	$ 11,410