Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2025	Nov. 12, 2025
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Period End Date	Sep. 30, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Entity Information [Line Items]
Entity Registrant Name	FIFTH ERA ACQUISITION CORP I
Entity Central Index Key	0002025401
Entity File Number	001-42539
Entity Tax Identification Number	36-5108801
Entity Incorporation, State or Country Code	E9
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	true
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Contact Personnel [Line Items]
Entity Address, Address Line One	PO Box 1093 Boundary Hall
Entity Address, Address Line Two	Cricket Square
Entity Address, City or Town	Grand Cayman
Entity Address, Country	KY
Entity Address, Postal Zip Code	KY1-1102
Entity Phone Fax Numbers [Line Items]
City Area Code	310
Local Phone Number	545-9265
Units, each consisting of one Class A ordinary share and one right
Entity Listings [Line Items]
Title of 12(b) Security	Units, each consisting of one Class A Ordinary Share and one Right
Trading Symbol	FERAU
Security Exchange Name	NASDAQ
Class A ordinary shares, par value $0.0001 per share
Entity Listings [Line Items]
Title of 12(b) Security	Class A Ordinary Shares, par value $0.0001 per share
Trading Symbol	FERA
Security Exchange Name	NASDAQ
Rights, each entitling the holder to receive one-tenth (1/10) of one Class A Ordinary Share upon the consummation of a Business Combination
Entity Listings [Line Items]
Title of 12(b) Security	Rights, each entitling the holder to receive one-tenth (1/10) of one Class A Ordinary Share upon the consummation of a Business Combination
Trading Symbol	FERAR
Security Exchange Name	NASDAQ
Class A Ordinary Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		23,600,000
Class B Ordinary Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		7,666,667

Fifth Era Acquisition Corp I 10-Q