Nature of Organization and Operations - Additional Information (Detail) $ in Millions	Jun. 30, 2022 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents and marketable securities	$ 852.8

Cash and cash equivalents and marketable securities.

No definition available.

Name:	apls_CashAndCashEquivalentsAndMarketableSecurities
Namespace Prefix:	apls_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant