Goodwill Impairment Charges (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 02, 2015
Goodwill and Patent Impairment Charges [Abstract]
Goodwill			$ 30,100
Share Price			$ 4.29	$ 16.72
Estimated Fair Value of the Reporting Unit			$ 252,000
Estimated Carrying Value of Reporting Unit, Market Capitalization Plus Cost Synergies Approach			344,300
Assets	$ 308,768	$ 296,003
Impairment of Goodwill	$ 0	$ 0	$ 30,149