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2. STOCK-BASED COMPENSATION - Options (Details 1) (Stock Options, USD $)
3 Months Ended 6 Months Ended
Nov. 30, 2014
Nov. 30, 2013
Nov. 30, 2014
Nov. 30, 2013
Stock Options
       
Expected term (in years) 4 years 4 years 4 years 4 years
Volatility 90.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
94.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
91.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
95.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Expected dividend $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
$ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
$ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
$ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Risk-free interest rates 1.11%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
0.95%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
1.25%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
1.40%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Estimated forfeiture rate 0.25%AEHR_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsEstimatedForfeitureRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
0.25%AEHR_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsEstimatedForfeitureRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
0.25%AEHR_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsEstimatedForfeitureRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
0.25%AEHR_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsEstimatedForfeitureRate
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Weighted average grant date fair value $ 1.32us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
$ 1.77us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
$ 1.64us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
$ 1.03us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember