Cover - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2025	May 31, 2025	Oct. 31, 2024
Cover [Abstract]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Apr. 30, 2025
Document Transition Report	false
Entity File Number	001-37784
Entity Registrant Name	GMS INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-2931287
Entity Address, Address Line One	115 Perimeter Center Place
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30346
City Area Code	(800)
Local Phone Number	392-4619
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	GMS
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 3,471.3
Entity Common Stock, Shares Outstanding		38,059,080
Entity Central Index Key	0001600438
Current Fiscal Year End Date	--04-30
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	true
Amendment Description	This Amendment No. 1 on Form 10-K/A (“Form 10-K/A”) to the Annual Report on Form 10-K of GMS Inc. (the “Company”) for the fiscal year ended April 30, 2025, filed with the Securities and Exchange Commission (the “SEC”) on June 18, 2025 (the “Original Form 10-K”), is being filed solely for the purpose of including the information required by Part III of Form 10-K that the Company did not include in the Original Form 10-K in reliance on General Instruction G(3) to Form 10-K. We are filing this Form 10-K/A to include Part III information in our Form 10-K because we do not intend to file a definitive proxy statement for an annual meeting of shareholders containing such information within 120 days after the end of our fiscal year ending April 30, 2025.On June 29, 2025, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with The Home Depot, Inc., a Delaware corporation (“Parent”), and Gold Acquisition Sub, Inc., a Delaware corporation and a wholly owned indirect subsidiary of Parent (“Merger Sub”). Pursuant to the terms of the Merger Agreement, on July 14, 2025, Merger Sub commenced a tender offer (as it may be extended, amended or supplemented from time to time, the “Offer”) to purchase, subject to certain conditions, any and all of the outstanding shares of common stock. Following the consummation of the Offer, Merger Sub will merge with and into the Company (the “Merger”) in accordance with the Merger Agreement and the Company will survive the Merger as the surviving corporation and will be an indirect, wholly owned subsidiary of Parent. The board of directors of the Company (the “Board”) has unanimously approved the Merger Agreement.In connection with the filing of this Form 10-K/A and pursuant to the rules of the SEC, we are including with this Form 10-K/A new certifications of our principal executive officer and principal financial officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. Item 15 of Part IV has also been amended to reflect the filing of these new certifications and the Merger Agreement exhibit.Except as described above, this Form 10-K/A does not modify or update the disclosures in, or any exhibits to, the Original Form 10-K. Furthermore, this Form 10-K/A does not change any previously reported financial results, nor does it reflect any events which occurred subsequent to the filing of the Original Form 10-K other than with respect to the Merger Agreement. Information not affected by this Form 10-K/A remains unchanged and reflects the disclosures made at the time the Original Form 10-K was filed.