Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

PCAOB issued Audit Firm Identifier

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 10-K
-Number 249
-Section 310

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 20-F
-Number 249
-Section 220
-Subsection f

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 40-F
-Number 249
-Section 240
-Subsection f

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2024	Feb. 28, 2025	Jun. 30, 2024
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2024
Document Annual Report	true
Document Transition Report	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Entity Registrant Name	GEN Restaurant Group, Inc.
Entity Central Index Key	0001891856
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Public Float			$ 58,775,840
Entity Interactive Data Current	Yes
Securities Act File Number	001-41727
Entity Tax Identification Number	87-3424935
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	11480 South Street Suite 205
Entity Address, City or Town	Cerritos
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90703
City Area Code	(562)
Local Phone Number	356-9929
Title of 12(b) Security	Class A Common stock,par value $0.001 per share
Trading Symbol	GENK
Security Exchange Name	NASDAQ
Documents Incorporated by Reference [Text Block]	Portions of the registrant’s definitive proxy statement relating to its 2025 annual meeting of stockholders are incorporated information by reference into Part III of this Annual Report on Form 10-K where indicated. Such proxy statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Auditor Name	Marcum LLP
Auditor Location	Costa Mesa, CA
Auditor Firm ID	688
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of GEN Restaurant Group, Inc. (the “Company”) as of December 31, 2024 and 2023, the related consolidated statements of income, changes in permanent equity (deficit) and cash flows for each of the two years in the period ended December 31, 2024, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with accounting principles generally accepted in the United States of America.
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,375,752
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		27,761,515