Segment Information Summarized Financial Information by Reportable Segments (Footnote) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Feb. 01, 2017
Segment Reporting Information [Line Items]
Loss on extinguishment of debt		$ 52,801	$ 0
Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Segment Reporting Information [Line Items]
Inventory markup	$ 23,000	23,000
Sales de Magnesio Ltda.
Segment Reporting Information [Line Items]
Percentage of equity interests acquired				50.00%
Cost of goods sold
Segment Reporting Information [Line Items]
Restructuring and other, net		2,900
Cost of goods sold | Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Segment Reporting Information [Line Items]
Utilization of inventory markup	11,900	22,500
Selling, general and administrative expenses
Segment Reporting Information [Line Items]
Restructuring and other, net	4,200	8,400
Reversal of purchase accounting accrual	1,000	1,000
Research and development expenses
Segment Reporting Information [Line Items]
Restructuring and other, net		5,800
Other expenses, net
Segment Reporting Information [Line Items]
Final settlement claims on previous business disposal	2,000	2,000
Revision of tax indemnification expense	$ 1,200	1,200
Asset retirement obligation charges		3,200
Loss on sale of properties		$ 2,100