Income Taxes - Income from Continuing Operations before Income Taxes Attributable to Geographic Locations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 148,500	$ 215,010	$ 123,153
Foreign	138,332	(55,151)	87,845
Income from continuing operations before income taxes	$ 286,832	$ 159,859	$ 210,998