| Cover | Jan. 12, 2024 |
| Entity Information [Line Items] | |
| Document Type | 8-K/A |
| Amendment Flag | true |
| Amendment Description | On January 12, 2024, Summit Materials, Inc. (the “Company”) filed a Current Report on Form 8-K (the “Original Form 8-K”) with the Securities and Exchange Commission (the “SEC”) to report the closing of the Company’s acquisition of all of the outstanding equity interests of Argos North America Corp., a Delaware corporation (“Argos USA”) from the Argos Parties (as defined below) (the “Transaction”) pursuant to that certain Transaction Agreement, dated as of September 7, 2023 (the “Transaction Agreement”) by and among Argos USA, Cementos Argos S.A., a sociedad anónima incorporated in the Republic of Colombia (“Cementos Argos”), Argos SEM, LLC, a Delaware limited liability company (“Argos SEM”), and Valle Cement Investments Inc., a sociedad anónima incorporated in the Republic of Panama (“Valle Cement” and, together with Argos SEM, the “Argos Parties”). |
| Document Period End Date | Jan. 12, 2024 |
| Entity File Number | 001-36873 |
| Entity Registrant Name | Summit Materials, Inc. |
| Entity Central Index Key | 0001621563 |
| Entity Tax Identification Number | 47-1984212 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1801 California Street |
| Entity Address, Address Line Two | Suite 3500 |
| Entity Address, City or Town | Denver |
| Entity Address, State or Province | CO |
| Entity Address, Postal Zip Code | 80202 |
| City Area Code | 303 |
| Local Phone Number | 893-0012 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock (par value, $0.01 per share) |
| Trading Symbol | SUM |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Summit Materials Llc [Member] | |
| Entity Information [Line Items] | |
| Entity File Number | 333-187556 |
| Entity Registrant Name | Summit Materials, LLC |
| Entity Central Index Key | 0001571371 |
| Entity Tax Identification Number | 26-4138486 |
| Entity Incorporation, State or Country Code | DE |
