Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Statements of Cash Flows
Cash issuance costs, Convertible preferred stock		$ 186
Cash issuance costs, Secondary public offering	$ 702

The cash outflow for cost incurred directly with the issuance of convertible preferred equity security.

No definition available.

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