Condensed Statements of Cash Flows (Parenthetical) $ in Thousands	9 Months Ended
Sep. 30, 2021 USD ($)
Condensed Statements of Cash Flows
Cash issuance costs, February Offering	$ 165

Amount of cash stock issuance costs subtracted from gross proceeds.

No definition available.

Name:	aplt_CashStockIssuanceCosts
Namespace Prefix:	aplt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration