Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Statement of Cash Flows [Abstract]
Related parties accounts payable and accrued expenses	$ 137	$ 2,719

Increase (decrease) in accounts payable and accrued expenses related parties.

No definition available.

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