INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE - Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Corporate Venture
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Ownership interest (as a percent)	100.00%	100.00%	100.00%	100.00%
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Ownership interest (as a percent)	49.00%	49.00%	49.00%	49.00%
Results of operations	$ 5.0	$ 0.5	$ 7.5	$ 0.5
Dividends received	$ 2.1	$ 2.3	$ 9.4	$ 7.2

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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