Company's Deferred Tax Assets, Net of Deferred Tax Liabilities and Valuation Allowance (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred tax assets, net of deferred tax liabilities	$ 20,455	$ 18,786
Valuation allowance	(1,507)	(1,507)
Deferred tax assets, net of deferred tax liabilities and valuation allowance	$ 18,948	$ 17,279