Income Taxes - Schedule of Income (Loss) Before Income Taxes and Adjustment for Noncontrolling Interests (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 138,477	$ 121,301	$ 117,388
Foreign	74,623	73,459	35,600
Income before income taxes	$ 213,100	$ 194,760	$ 152,988