Document and Entity Information - USD ($)	12 Months Ended
	Jan. 02, 2024	Feb. 26, 2024	Jul. 04, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jan. 02, 2024
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	BJRI
Entity Registrant Name	BJ’S RESTAURANTS, INC.
Entity Central Index Key	0001013488
Current Fiscal Year End Date	--01-02
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		23,366,951
Entity Public Float			$ 747,725,214
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	CA
Entity Tax Identification Number	33-0485615
Entity Address, Address Line One	7755 Center Avenue
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	Huntington Beach
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92647
City Area Code	(714)
Local Phone Number	500-2400
Title of 12(b) Security	Common Stock, No Par Value
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity File Number	0-21423
Documents Incorporated by Reference	Certain portions of the following documents are incorporated by reference into Part III of this Form 10-K: The Registrant’s Proxy Statement for the Annual Meeting of Shareholders to be held on June 18, 2024.
Auditor Firm ID	185
Auditor Name	KPMG LLP
Auditor Location	Los Angeles, California
Document Financial Statement Error Correction [Flag]	false