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Stock Based Compensation Stock Option Activity (Detail) (USD $)
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6 Months Ended |
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Mar. 31, 2015
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| Option Shares Outstanding | |
| Outstanding, Beginning Balance | 8,637,962us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Awarded | 2,987,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross |
| Exercised | 0us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |
| Forfeited | 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod |
| Outstanding, Ending Balance | 11,625,462us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Vested | 7,399,875us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares |
| Vested and expected to vest | 11,625,492us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber |
| Weighted Average Exercise Price | |
| Outstanding, Beginning Balance | $ 0.38us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| Awarded | $ 0.19us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice |
| Exercised | $ 0us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice |
| Outstanding, Ending Balance | $ 0.31us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| Vested | $ 0.32arth_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedWeightedAverageExercisePrice |
| Vested and expected to vest | $ 0.31us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice |
| Weighted Average Remaining Contractual Term (years) | |
| Awarded | 0 years |
| Exercised | 0 years |
| Forfeited | 0 years |
| Balance | 5 years 4 months 28 days |
| Vested | 4 years 10 months 2 days |
| Vested and expected to vest | 5 years 4 months 28 days |
| Aggregate Intrinsic Value | |
| Outstanding, Beginning Balance | $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue |
| Awarded | 0arth_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAwardedAggregateIntrinsicValue |
| Exercised | 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue |
| Forfeited | 0arth_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodAggregateIntrinsicValue |
| Outstanding, Ending Balance | 7,750us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue |
| Vested | 5,243arth_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodAggregateIntrinsicValue |
| Vested and expected to vest | $ 7,750us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue |
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- Details
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- Definition
Share based compensation arrangement by share based payment award options awarded aggregate intrinsic value. No definition available.
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- Definition
share based compensation arrangement by share based payment award options awarded weighted average remaining contractual term. No definition available.
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- Definition
Share based compensation arrangement by share based payment award options exercised weighted average remaining contractual term. No definition available.
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- Definition
Share based compensation arrangement by share based payment award options forfeited in period aggregate intrinsic value. No definition available.
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- Definition
Share based compensation arrangement by share based payment award options forfeited weighted average remaining contractual term. No definition available.
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- Definition
Share based compensation arrangement by share based payment award options vested in period aggregate intrinsic value. No definition available.
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- Definition
Share based compensation arrangement by share based payment award options vested weighted average exercise price. No definition available.
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- Definition
Share based compensation arrangement by share based payment award options vested weighted average remaining contractual term. No definition available.
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- Details
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- Details
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- Definition
Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Gross number of share options (or share units) granted during the period. No definition available.
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- Definition
Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average remaining contractual term for fully vested and expected to vest options that are exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of options vested. No definition available.
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- Definition
Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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- Definition
Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
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- Definition
Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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