Income Taxes from Continuing Operations - The Geographical Allocation of the Companys Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Pre-tax (loss) income from continuing U.S. operations	$ (49,572)	$ 287,880	$ 241,665
Pre-tax loss from continuing foreign operations	(9,626)	(16,580)	(9,509)
Total pre-tax (loss) income from continuing operations	$ (59,198)	$ 271,300	$ 232,156