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STOCKHOLDERS' EQUITY AND SHARE-BASED COMPENSATION EXPENSE - Assumptions Used to Value Employees Stock Purchase Rights (Details)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Stockholders Equity And Share Based Compensation Expense [Abstract]    
Risk free interest rate 0.07%affx_Share-BasedCompensationArrangementByShare-BasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateEspp 0.16%affx_Share-BasedCompensationArrangementByShare-BasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateEspp
Expected dividend yield 0.00%affx_Share-BasedCompensationArrangementByShare-BasedPaymentAwardFairValueAssumptionsExpectedDividendRateForEspp 0.00%affx_Share-BasedCompensationArrangementByShare-BasedPaymentAwardFairValueAssumptionsExpectedDividendRateForEspp
Expected volatility 72.00%affx_Share-BasedCompensationArrangementByShare-BasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateEspp 60.00%affx_Share-BasedCompensationArrangementByShare-BasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateEspp
Expected term (in years) 9 months 9 months