Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 50
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Loans to and Investments in Associated Companies - Golden Queen Mining Company Narrative (Details) - USD ($) $ in Millions	24 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2014
Golden Queen Mining Company, LLC
Investment [Line Items]
Prior ownership percentage			100.00%
Percentage of ownership owned		35.00%
Golden Queen Mining Co, Ltd
Investment [Line Items]
Ownership percentage		50.00%
Gauss LLC
Investment [Line Items]
Cash invested in Limited Liability Company	$ 83.0
Gauss LLC \| Golden Queen Mining Company, LLC
Investment [Line Items]
Total investment in associated company		$ 117.5
Percentage of ownership owned		50.00%
Clay Family
Investment [Line Items]
Contributions from noncontrolling interests	$ 34.5