Cover - USD ($) $ in Thousands	12 Months Ended
Cover - USD ($) $ in Thousands	Dec. 31, 2025	Apr. 26, 2026
Document Information [Line Items]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-42888
Registrant Name	Fermi Inc.
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	33-3560468
Entity Address, Address Line One	620 S. Taylor St.
Entity Address, Address Line Two	Suite 301
Entity Address, City or Town	Amarillo
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	79101
City Area Code	(214)
Local Phone Number	894-7855
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		637,574,239
Entity Central Index Key	0002071778
Amendment Flag	true
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2025
Entity Public Float	$ 0
Amendment Description	This Amendment No. 1 (“Amendment”) on Form 10-K/A is filed (i) pursuant to General Instruction G(3) of Form 10-K, as we do not intend to file a definitive proxy statement for the 2026 annual meeting of stockholders within 120 days of the end of our fiscal year ended December 31, 2025, and (ii) to amend Part IV, Item 15 (Exhibits and Financial Statement Schedules) of the Annual Report on Form 10-K of Fermi Inc. (the “Company”) for the period from January 10, 2025 (Inception) through December 31, 2025, as filed on March 30, 2026 (the "Original Form 10-K”). Accordingly, this amendment is being filed solely to: •include the information required by Part III, Items 10 (Directors, Executive Officers and Corporate Governance), 11 (Executive Compensation), 12 (Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters), 13 (Certain Relationships and Related Transactions, and Director Independence) and 14 (Principal Accountant Fees and Services) of Form 10-K;•amend the reference on the cover page of our Original Form 10-K to reflect that no documents will be incorporated by reference into our Original Form 10-K;•file new certifications of our principal executive officer and principal financial officer pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”); and •include the Fermi Inc. Compensation Recovery Policy as an exhibit. As required by Rule 12b-15 under the Exchange Act, new certifications by the Company’s principal executive officer and principal financial officer are filed herewith as exhibits to this Amendment pursuant to Rule 13a-14(a) or 15d-14(a) of the Exchange Act. As no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4, and 5 of the certifications have been omitted. Additionally, because this Amendment does not include financial statements, the Company is not including certifications pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.Except as described above, this Amendment does not modify or update disclosure in, or exhibits to, the Original Form 10-K. Furthermore, this Amendment does not change any previously reported financial results, nor does it reflect events occurring after the date of the Original Form 10-K. As such, information not affected by this Amendment remains unchanged and reflects the disclosures made at the time the Original Form 10-K was filed. Accordingly, this Amendment should be read in conjunction with the Original Form 10-K and other filings of the Company with the Securities and Exchange Commission.
Common Stock, $0.001 par value at Nasdaq Stock Market LLC
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	FRMI
Security Exchange Name	NASDAQ
Common Stock, $0.001 par value at London Stock Exchange
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	FRMI

Fermi Inc. 10-K/A