Acquisitions (Details) - USD ($) $ in Thousands			12 Months Ended
	Feb. 01, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Gain on acquisition			$ 0	$ 6,221	$ 0
Other acquisitions			11,403	44,367	126,747
Goodwill		$ 1,540,032	1,567,169	1,610,355	1,540,032
Inventories			700,540	592,781
Acquisition and integration related costs			0	0	57,384
Sales de Magnesio Ltda.
Business Acquisition [Line Items]
Percentage of equity interests acquired	50.00%
Total purchase price	$ 8,300
Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Business Acquisition [Line Items]
Other acquisitions		$ 145,000
Accounts receivable				600
Property, plant and equipment				24,100
Other intangibles				46,300
Accounts payable				2,800
Deferred tax liabilities				6,300
Fair value of net working capital				6,200
Inventories				37,100
Inventory markup				23,100
Acquired finite-lived intangible assets, weighted average useful life		17 years
Rockwood Holdings, Inc.
Business Acquisition [Line Items]
Acquisition and integration related costs					52,100
Other significant projects
Business Acquisition [Line Items]
Acquisition and integration related costs					5,300
Patents and technology | Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		20 years
Customer lists and relationships | Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		13 years
Other | Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		20 years
Other expenses, net | Sales de Magnesio Ltda.
Business Acquisition [Line Items]
Gain on acquisition				6,200
Cost of sales
Business Acquisition [Line Items]
Acquisition and integration related costs			3,700	14,300
Selling, general and administrative expenses
Business Acquisition [Line Items]
Acquisition and integration related costs			15,700	19,600
Reportable Segments | Lithium
Business Acquisition [Line Items]
Goodwill		$ 1,326,980	$ 1,354,779	1,389,089	$ 1,326,980
Reportable Segments | Lithium | Jiangxi Jiangli New Materials Science and Technology Co. Ltd.
Business Acquisition [Line Items]
Goodwill				$ 83,100