Conversion price percentage of Average closing sale price.

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

Conversion Price Percentage Of Closing Trading Share Price

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Convertible debt.

+ References

No definition available.

+ Details

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- Definition

Debt instrument convertible threshold percentage of conversion amount of debt.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
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- Definition

Debt prepayment fee percentage after second anniversary before maturity.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Debt prepayment fee percentage on or after first anniversary.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Debt Prepayment Fee Percentage On Original Aggregate Principal

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Share holding percentage of shares issued and outstanding.

+ References

No definition available.

+ Details

Name:	achv_ShareHoldingPercentageOfSharesIssuedAndOutstanding
Namespace Prefix:	achv_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of conversion of original debt instrument in noncash or part noncash transaction.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
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Balance Type:	na
Period Type:	instant

- Definition

Price of the entity's common stock which would be required to be attained for the conversion feature embedded in the debt instrument to become effective.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

States whether the entity was in compliance with the debt covenants throughout the reporting period, and describes facts and circumstances of any compliance failure.

+ References

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Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

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Convertible Debt - Additional Information (Details) $ / shares in Units, $ in Millions		1 Months Ended	12 Months Ended
	Jul. 25, 2024 USD ($) Days $ / shares	Oct. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)
Convertible Term Loan [Member]
Convertible Debt [Line Items]
Debt Conversion, Description	conversion price equal to the greater of (i) $4.854, subject to customary adjustment provisions, and (ii) the lower of (a) 150% of the average of the closing sale price of our common stock during the 10 trading days preceding the effective date of such tranche and (b) 150% of the closing sale price of our common stock on the trading day immediately preceding the effective date of such tranche.
Contingent Convertible Debt Agreement [Member]
Convertible Debt [Line Items]
Covenant compliance			As of December 31, 2025, we are in compliance with all covenants under the New Debt Agreement.
SVB and Lender [Member] \| Contingent Convertible Debt Agreement [Member] \| Convertible Term Loan [Member]
Convertible Debt [Line Items]
Convertible debt principal amount \| $	$ 10.0	$ 5.0	$ 5.0
Maturity date	Jun. 01, 2028
Conversion price per share	$ 7
Conversion price percentage of average closing sale price	150.00%
Conversion price percentage of closing trading share price	150.00%
Stock trigger price	$ 24
Threshold consecutive trading days \| Days	10
Threshold percentage of conversion amount of debt	50.00%
Prepayment fee percentage on or after first anniversary	2.00%
Prepayment fee percentage after second anniversary before maturity	1.00%
Prepayment fee percentage on original aggregate principal	4.00%
SVB and Lender [Member] \| Contingent Convertible Debt Agreement [Member] \| Convertible Term Loan [Member] \| Minimum [Member]
Convertible Debt [Line Items]
Conversion price per share	$ 4.854
SVB and Lender [Member] \| Convertible Debt Agreement [Member] \| Convertible Term Loan [Member]
Convertible Debt [Line Items]
Convertible debt principal amount \| $		$ 5.0
Convertible debt, interest rate		1.00%
Convertible debt, stated rate		7.00%
SVB and Lender [Member] \| Registration Rights Agreement [Member]
Convertible Debt [Line Items]
Share holding percentage of shares issued and outstanding	7.00%