Summary of significant accounting policies - Stock-based compensation (Details) - $ / shares	Jul. 15, 2019	Dec. 31, 2018	Oct. 02, 2017	May 31, 2016
Summary of significant accounting policies
Fair value of unlisted common stock	$ 10.95	$ 3.18	$ 1.01	$ 0.92

Third party valuation of unlisted common stock using probability weighed expected return method where the equity value in one or more scenarios is calculated using an option pricing method.

No definition available.

Name:	apre_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsValuationOfUnlistedCommonStockPerShare
Namespace Prefix:	apre_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant