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SHORT-TERM INVESTMENTS: (Details) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Investments    
Trading Securities, Debt $ 333,700,000us-gaap_TradingSecuritiesDebt $ 202,600,000us-gaap_TradingSecuritiesDebt
Weighted average interest rate (as a percent) 0.78%scco_TradingSecuritiesWeightedAverageInterestRate 3.78%scco_TradingSecuritiesWeightedAverageInterestRate
Available for sale 4,900,000us-gaap_AvailableForSaleSecuritiesCurrent 5,700,000us-gaap_AvailableForSaleSecuritiesCurrent
Weighted average interest rate (as a percent) 0.44%scco_AvailableForSaleSecuritiesWeightedAverageInterestRate 0.42%scco_AvailableForSaleSecuritiesWeightedAverageInterestRate
Total short-term investments 338,589,000us-gaap_ShortTermInvestments 208,268,000us-gaap_ShortTermInvestments
Trading:    
Interest earned 4,900,000us-gaap_InterestAndDividendIncomeSecuritiesTradingOrMeasuredAtFairValue 5,200,000us-gaap_InterestAndDividendIncomeSecuritiesTradingOrMeasuredAtFairValue
Unrealized gain (loss) at the end of the period 2,100,000us-gaap_TradingSecuritiesUnrealizedHoldingLoss (1,900,000)us-gaap_TradingSecuritiesUnrealizedHoldingLoss
Available-for-sale    
Investment redeemed 800,000us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities 800,000us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities
Contractual maturities of the Company's available for sale debt securities    
One year or less 300,000us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue 400,000us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue
Maturing after five years through ten years 100,000us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue 200,000us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue
Due after 10 years 4,500,000us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue 5,100,000us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue
Total debt securities 4,900,000us-gaap_AvailableForSaleSecuritiesDebtSecurities 5,700,000us-gaap_AvailableForSaleSecuritiesDebtSecurities
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