Summary of Significant Accounting Policies (Details) $ in Millions	Feb. 28, 2017 USD ($)
Prepaid Expenses and Other Current Assets [Member]
PDUFA fee paid for which waiver has been applied	$ 2.0

The amount of fees paid in connection with regulatory approval of the entity's product.

No definition available.

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