COVER - shares shares in Millions	9 Months Ended
	Sep. 30, 2025	Nov. 03, 2025
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	001-41704
Entity Registrant Name	FORTREA HOLDINGS INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	92-2796441
Entity Address, Address Line One	8 Moore Drive
Entity Address, City or Town	Durham
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27713
City Area Code	(877)
Local Phone Number	495-0816
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		92.4
Amendment Flag	false
Entity Central Index Key	0001965040
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2025
Current Fiscal Year End Date	--12-31
Common Class A
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	FTRE
Security Exchange Name	NASDAQ
Preferred Class A
Document Information [Line Items]
Title of 12(b) Security	Rights to Purchase Series A Preferred Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
No Trading Symbol Flag	true