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Income Tax - Schedule of Income Tax (Parentheticals) (Details)	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023
Schedule of Income Tax [Abstract]
Prima facie tax on net loss before income tax	25.00%	25.00%	25.00%

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- Definition

Prima facie tax on net loss before income tax.

+ References

No definition available.

+ Details

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Namespace Prefix:	athe_
Data Type:	dtr:percentItemType
Balance Type:	na
Period Type:	duration

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- References

No definition available.

+ Details

Name:	athe_ScheduleOfIncomeTaxAbstract
Namespace Prefix:	athe_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration