Cover Page - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Apr. 01, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K/A
Amendment Flag	true
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	MGRC
Entity Registrant Name	McGRATH RENTCORP
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock
Entity Interactive Data Current	Yes
Entity File Number	000-13292
Entity Incorporation, State or Country Code	CA
Entity Tax Identification Number	94-2579843
Entity Address, Address Line One	5700 Las Positas Road
Entity Address, City or Town	Livermore
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94551-7800
City Area Code	925
Local Phone Number	606-9200
Document Annual Report	true
Document Transition Report	false
Entity Central Index Key	0000752714
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Common Stock, Shares Outstanding		24,548,743
Document Financial Statement Error Correction [Flag]	false
Entity Public Float			$ 2,264,372,153
Documents Incorporated by Reference [Text Block]	None
Amendment Description	EXPLANATORY NOTE McGrath Rentcorp (the “Company”) is filing this Amendment to amend its Annual Report on Form 10-K (the “Form10-K”) for the fiscal year ended December 31, 2023, originally filed with the U.S. Securities and Exchange Commission (the “SEC”) on February 21, 2024 (the “Original Annual Report”), to provide the information required by Part III of Form 10-K. In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934 (the “Exchange Act”), new certifications by our principal executive officer and principal financial officer under Section 302 of the Sarbanes-Oxley Act of 2002 are being filed as exhibits to this Amendment under Item 15 of Part IV. Because no financial statements are contained within this Amendment, we are not filing currently dated certifications pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. This Amendment also amends the cover page to update the number of shares of our common stock outstanding and to remove the statement that information is being incorporated by reference from our definitive proxy statement. Except as described above, no other changes have been made to the Original Annual Report. The Original Annual Report continues to speak as of the date on which it was filed, and we have not updated the disclosures contained therein to reflect any events which occurred at a date subsequent to the date on which it was filed. Accordingly, this Amendment should be read in conjunction with the Original Annual Report and with our other filings made with the SEC subsequent to the filing of the Original Annual Report.