INCOME TAXES: (Details) (USD $)	3 Months Ended						1 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Peru	Mar. 31, 2013 Peru	Mar. 31, 2014 Peru Minimum	Mar. 31, 2014 Peru Maximum	Jan. 31, 2014 Mexican Operations	Mar. 31, 2014 Mexican Operations
INCOME TAXES:
Income tax provision	$ 204,162,000	$ 238,879,000
Effective income tax rate (as a percent)	39.10%	32.80%
Increase in effective tax rate (as a percent)	5.10%
Income Taxes
Mining royalty tax (as a percent)					1.00%	12.00%	7.50%
Royalty charge assessed as a percentage of net sales					1.00%
Operating income margin for royalty tax (as a percent)						10.00%
Increment in operating income margin for royalty tax (as a percent)					5.00%	12.00%
Increase in royalty tax rate for each 5% increase up to 12% increase in operating income margin (as a percent)			0.75%
Royalty charge			7,700,000	10,600,000
Provision for royalty tax			1,600,000	3,900,000
Provision for royalty tax								24,000,000
Additional royalty tax over net sales from sales of gold, silver and platinum (as a percent)							0.50%
Special mine tax (as a percent)					2.00%	8.40%
Operating income margin (as a percent)						10.00%
Increment in operating income margin (as a percent)					5.00%	85.00%
Increase in special mining tax rate for each 5% increase up to 85% increase in operating income margin (as a percent)			0.40%
Provision for special mining tax			$ 12,000,000	$ 15,500,000