Subsequent Events (Details) - Subsequent event $ in Thousands	Oct. 10, 2019 USD ($)
Subsequent events
Repayment of loan	$ 30,000
Loan and Security Agreement
Subsequent events
Repayment of loan	30,000
Payment of interest	70
Final payment fee	1,725
Prepayment fee	600
EPI Health
Subsequent events
Cash consideration	55,000
Upfront payment receivable	35,000
Escrow deposit	1,750
Potential threshold sales milestone	$ 20,000
Period of royalty payment from first commercial sale	10 years
Percentage of payments received in connection with license or sublicense of assets transferred	25.00%
Payment for certain inventory	$ 200

The carrying amount as on the date of consideration held in escrow under the asset purchase agreement.

No definition available.

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

- Definition

The amount agreed to be paid by the buyer for certain inventory, subject to a specified post-closing inventory-related adjustment as a part of the asset purchase agreement.

+ References

No definition available.

+ Details

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

- Definition

The amount of potential threshold sales milestone as on the date of consideration.

+ References

No definition available.

+ Details

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

- Definition

The carrying amount as on the date of upfront payment receivable by the Company under the asset purchase agreement.

+ References

No definition available.

+ Details

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

- Definition

The amount of final payment fee incurred in connection with repayment of debt.

+ References

No definition available.

+ Details

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

- Definition

The amount of prepayment fee incurred in connection with repayment of debt.

+ References

No definition available.

+ Details

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

- Definition

The amount agreed to be paid by the buyer as a percentage of any upfront, license, milestone, maintenance or fixed payment received by the buyer in connection with any license or sublicense of the assets transferred in the disposition.

+ References

No definition available.

+ Details

Name:	acrs_PercentageOfPaymentsReceivedInConnectionWithLicenseOrSublicenseOfAssetsTransferred
Namespace Prefix:	acrs_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of royalty payment from the date of the first commercial sale of the product.

+ References

No definition available.

+ Details

Name:	acrs_PeriodOfRoyaltyPaymentFromFirstCommercialSale
Namespace Prefix:	acrs_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

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

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

+ Details

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

- Definition

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfSecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

No definition available.

+ 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_DebtInstrumentAxis=acrs_LoanAndSecurityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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