Supplemental Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Long Lived Assets Held-for-sale [Line Items]
Gain from antitrust litigation settlement	$ (3,591)
Gain (loss) on disposition of assets		$ (900)
Belgium
Long Lived Assets Held-for-sale [Line Items]
Gain (loss) on disposition of assets		$ (900)