Summary of significant accounting policies, Income taxes and Segment reporting (Details)	12 Months Ended
Dec. 31, 2017 Segment
Income taxes [Abstract]
Tax loss carryforward period	7 years
Segment reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

The period or time limit over which financial losses of the entity for preceding years can be deducted from the taxable revenue for a period.

No definition available.

Name:	aciu_IncomeTaxLossCarryforwardPeriod
Namespace Prefix:	aciu_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration