Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Other Assets — Long-term	$ 2,816	$ 2,644
Deferred Tax Liabilities — Long-term	(5,121)	(11,297)
Net Deferred Tax Liabilities	$ (2,305)	$ (8,653)