Intangible Assets and Goodwill - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Goodwill
Goodwill			$ 90,976
Goodwill asset impaired		$ 90,976
Glemba
Goodwill
Amount of carrying amount in excess of fair value amount		$ 91,000
Goodwill asset impaired	$ 91,000