Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Research and development expenses, related party	$ 760	$ 2,123
Selling, General and administrative expenses, related party	$ 55	$ 0

Selling, general and administrative expense related party.

No definition available.

Name:	phat_SellingGeneralAndAdministrativeExpenseRelatedParty
Namespace Prefix:	phat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration