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SHORT-TERM INVESTMENTS: (Details) (USD $)
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Investments      
Trading securities $ 79,100,000us-gaap_TradingSecurities   $ 333,700,000us-gaap_TradingSecurities
Weighted average interest rate (as a percent) 1.16%scco_TradingSecuritiesWeightedAverageInterestRate   0.78%scco_TradingSecuritiesWeightedAverageInterestRate
Available-for-sale 4,700,000us-gaap_AvailableForSaleSecuritiesCurrent   4,900,000us-gaap_AvailableForSaleSecuritiesCurrent
Weighted average interest rate (as a percent) 0.46%scco_AvailableForSaleSecuritiesWeightedAverageInterestRate   0.44%scco_AvailableForSaleSecuritiesWeightedAverageInterestRate
Total short-term investments 83,820,000us-gaap_ShortTermInvestments   338,589,000us-gaap_ShortTermInvestments
Trading:      
Interest earned 300,000us-gaap_InterestAndDividendIncomeSecuritiesTradingOrMeasuredAtFairValue 1,400,000us-gaap_InterestAndDividendIncomeSecuritiesTradingOrMeasuredAtFairValue  
Unrealized gain (loss) at the end of the period 2,800,000us-gaap_TradingSecuritiesUnrealizedHoldingLoss 2,200,000us-gaap_TradingSecuritiesUnrealizedHoldingLoss  
Available-for-sale      
Investment redeemed 200,000us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities    
Maximum      
Available-for-sale      
Interest earned $ 100,000us-gaap_InterestAndDividendIncomeSecuritiesAvailableForSale
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		 $ 100,000us-gaap_InterestAndDividendIncomeSecuritiesAvailableForSale
/ us-gaap_RangeAxis
= us-gaap_MaximumMember