Commitments and Contingencies (Details) - Stanford - Maximum $ in Millions	3 Months Ended
Mar. 31, 2022 USD ($)
Commitments And Contingencies
Annual license maintenance fees	$ 0.1
Milestones payable upon event	$ 1.1

The amount the Company will pay for regulatory milestones on each licensed product upon the occurrence of specific events as outlined in the license agreement.

No definition available.

Name:	fhtx_MilestonesPayableUponEvent
Namespace Prefix:	fhtx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration