Subsequent Events (Details) - Subsequent event $ in Millions	1 Months Ended
Jul. 31, 2024 USD ($)
Royalty purchase agreement \| OMERS
Subsequent Event [Line Items]
Proceeds from upfront payment	$ 26.5
Additional amount receivable on achievement of sales milestones	$ 5.0
Non-Exclusive Patent License Agreement \| Eli Lilly and Company \| OMERS
Subsequent Event [Line Items]
Percentage of remaining anniversary milestone payments payable acquired	100.00%

Amount of receivable from additional payments based on the achievement of certain sales milestones pursuant to the agreement.

No definition available.

+ Details

Name:	acrs_AdditionalAmountReceivableOnAchievementOfSalesMilestones
Namespace Prefix:	acrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percent of remaining anniversary milestone payments payable acquired pursuant to the agreement.

+ References

No definition available.

+ Details

Name:	acrs_PercentageOfRemainingAnniversaryMilestonePaymentsPayableAcquired
Namespace Prefix:	acrs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash inflow from upfront payment received pursuant to the agreement.

+ References

No definition available.

+ Details

Name:	acrs_ProceedsFromUpfrontPayment
Namespace Prefix:	acrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481674/830-30-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483399/855-10-50-2

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_CounterpartyNameAxis=acrs_OntarioMunicipalEmployeesRetirementSystemMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_CounterpartyNameAxis=acrs_EliLillyAndCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=acrs_OntarioMunicipalEmployeesRetirementSystemMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: