Income Taxes - Schedule of Income from Continuing Operations before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
United States	$ 54,212	$ 53,356	$ 64,923
Foreign	7,107	1,583	6,100
Total income before income taxes	$ 61,319	$ 54,939	$ 71,023