Amount of amendment fees payable due to amendment in agreement.

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of amendment fees payable per installment due to amendment in agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

The amount of aggregate payment agreed to be made by the company on achievement of certain development milestones.

+ References

No definition available.

+ Details

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- Definition

Future payments that could be paid upon achievement of certain milestones per agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

The number of installments for payments to be made or received under the agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Cash outflow for milestone achieved per agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Future payments that could be paid upon achievement of certain milestones per agreement.

+ References

No definition available.

+ Details

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

- Definition

The minimum period before expiration of the agreement, starting from agreement effective date.

+ References

No definition available.

+ Details

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- 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

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

- Definition

Amount of expense related to royalty payments under a contractual arrangement such as payment for mineral and drilling rights and use of technology or intellectual property.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

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

- Details

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- Details

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- Details

Name:	srt_CounterpartyNameAxis=acrs_RigelPharmaceuticalsIncMember
Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=acrs_A101ProductMember
Namespace Prefix:
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Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=acrs_AchievementOfSpecifiedCommercialMilestonesMember
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- Details

Name:	us-gaap_TypeOfArrangementAxis=acrs_AssetPurchaseAgreementEncompassingWorldwideRightsToOxymetazolineHydrochlorideCreamPlusIntellectualPropertyMember
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- Details

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Agreements Related to Intellectual Property (Details) $ in Thousands	1 Months Ended				3 Months Ended		9 Months Ended
	Nov. 30, 2018 USD ($)	May 31, 2018 USD ($)	Apr. 30, 2017 USD ($)	Aug. 31, 2012	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Oct. 31, 2019 USD ($) installment	Aug. 31, 2015 USD ($)
Allergan \| Achievement Of Development Milestones
Agreements Related to Intellectual Property
Milestone payment	$ 5,000
Rigel
Agreements Related to Intellectual Property
Potential milestones payable					$ 10,000		$ 10,000
Milestone payment					4,000
Aggregate milestone payments										$ 80,000
Assignment Agreement and Finder's Services Agreement \| A-101 45% Topical Solution
Agreements Related to Intellectual Property
Term of agreement, minimum				15 years
Finder's Services Agreement \| Achievement Of Specified Commercial Milestones
Agreements Related to Intellectual Property
Aggregate royalty payments							14	$ 0
Finder's Services Agreement \| Achievement Of Specified Commercial Milestones \| A-101 45% Topical Solution
Agreements Related to Intellectual Property
Milestone payment		$ 1,500	$ 1,000
Potential future milestone payments							3,000
APA \| Allergan
Agreements Related to Intellectual Property
Aggregate royalty payments					$ 440	$ 0	$ 1,281	$ 0
Subsequent event \| Rigel
Agreements Related to Intellectual Property
Potential milestones payable									$ 10,500
Amendment fees payable									$ 1,500
Number of installments \| installment									3
Amendment fees payable, per installment									$ 500