Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements Using Significant Unobservable Inputs Level 3 (Detail)

v2.4.1.9
Fair Value Measurements Using Significant Unobservable Inputs Level 3 (Detail) (USD $)
3 Months Ended 6 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Beginning balance at September 30, 2014     $ 6,270,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue  
Modification of Warrants 624,016arth_GainOnWarrantDerivativeModification   1,924,186arth_GainOnWarrantDerivativeModification  
Exercises of Warrants 0arth_GainOnExerciseOfWarrants 0arth_GainOnExerciseOfWarrants 224,000arth_GainOnExerciseOfWarrants 0arth_GainOnExerciseOfWarrants
Adjustments to estimated fair value 0arth_FairValueOfDerivativeLiabilitiesInExcessOfProceeds (7,541,693)arth_FairValueOfDerivativeLiabilitiesInExcessOfProceeds 0arth_FairValueOfDerivativeLiabilitiesInExcessOfProceeds (7,541,693)arth_FairValueOfDerivativeLiabilitiesInExcessOfProceeds
Ending balance at March 31, 2015 4,213,595us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue   4,213,595us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue  
Fair Value, Inputs, Level 3        
Beginning balance at September 30, 2014     6,270,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ dei_LegalEntityAxis
= us-gaap_FairValueInputsLevel3Member
 
Modification of Warrants     1,924,186arth_GainOnWarrantDerivativeModification
/ dei_LegalEntityAxis
= us-gaap_FairValueInputsLevel3Member
 
Exercises of Warrants     (224,000)arth_GainOnExerciseOfWarrants
/ dei_LegalEntityAxis
= us-gaap_FairValueInputsLevel3Member
 
Adjustments to estimated fair value     (3,756,591)arth_FairValueOfDerivativeLiabilitiesInExcessOfProceeds
/ dei_LegalEntityAxis
= us-gaap_FairValueInputsLevel3Member
 
Ending balance at March 31, 2015 $ 4,213,595us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ dei_LegalEntityAxis
= us-gaap_FairValueInputsLevel3Member
  $ 4,213,595us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ dei_LegalEntityAxis
= us-gaap_FairValueInputsLevel3Member