Summary of Significant Accounting Policies (Details)	6 Months Ended
Jun. 30, 2019 USD ($)	Jun. 30, 2018 item	Dec. 31, 2018 USD ($)
Revenue Recognition
Revenue, Practical Expedient, Financing Component [true false]	true
Revenue, Practical Expedient, Incremental Cost of Obtaining Contract [true false]	true
Number of active research grants \| item		2
Remaining funds available to the Company under grants	$ 0
Inventory
Inventory	$ 185,000		$ 791,000

The number of active research grants from which the entity receives revenue.

No definition available.

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Period Type:	duration

- Definition

The amount of remaining funds available to the Company under contracted research grants.

+ References

No definition available.

+ Details

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Namespace Prefix:	acrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- References

No definition available.

+ Details

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- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765

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-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Indicates (true false) whether practical expedient was elected not to adjust consideration for effect of financing component when transfer and customer payment for product or service occurs within one year or less.

+ References

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- Definition

Indicates (true false) whether practical expedient was elected to recognize incremental cost of obtaining contract as expense when incurred if amortization period would have been one year or less.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 22
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-SubTopic 40
-Section 50
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