Income Taxes - Summary of Income from Continuing Operations before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
Foreign	$ 82,919	$ 33,611	$ 35,571
United States	21,431	31,118	2,364
Income from continuing operations before income taxes	$ 104,350	$ 64,729	$ 37,935