Area of office space leased.

No definition available.

Name:	achv_AreaOfOfficeSpaceLeased
Namespace Prefix:	achv_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Indemnification expense.

+ References

No definition available.

+ Details

Name:	achv_IndemnificationExpense
Namespace Prefix:	achv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Lease agreement commencement date.

+ References

No definition available.

+ Details

Name:	achv_LeaseAgreementCommencementDate
Namespace Prefix:	achv_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

+ Details

Name:	us-gaap_OperatingLeaseExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash payments to lessor's for use of assets under operating leases.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (g)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-25

+ Details

Name:	us-gaap_PaymentsForRent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_TypeOfArrangementAxis=achv_VancouverOfficeOperatingLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_CA-BC
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Additional Information (Detail)				3 Months Ended		6 Months Ended
	Dec. 09, 2024	Dec. 16, 2022	Nov. 19, 2018 USD ($) ft²	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)
Other Commitments [Line Items]
Consolidated rent expense				$ 30,000	$ 29,000	$ 61,000	$ 58,000
Indemnification obligations				$ 0		0
Expenses related to indemnification issues						$ 0
Vancouver Office Operating Lease [Member] \| Vancouver, British Columbia [Member]
Other Commitments [Line Items]
Lease agreement commencement date	Feb. 01, 2025	Feb. 01, 2023	Feb. 01, 2019
Area of office space leased \| ft²			2,367
Operating lease, term of contract			4 years
Lessee, Operating Lease, Existence of Option to Extend [true false]		true
Operating lease, extension term	2 years	2 years
Annual rent expense			$ 100,000