| Cover | Jul. 30, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 30, 2024 |
| Entity File Number | 333-278185 |
| Entity Registrant Name | Smurfit Westrock plc |
| Entity Central Index Key | 0002005951 |
| Entity Tax Identification Number | 98-1776979 |
| Entity Incorporation, State or Country Code | L2 |
| Entity Address, Address Line One | Beech Hill |
| Entity Address, Address Line Two | Clonskeagh |
| Entity Address, City or Town | Dublin 4 |
| Entity Address, Country | IE |
| Entity Address, Postal Zip Code | D04 N2R2 |
| City Area Code | 353 |
| Local Phone Number | 1 202 7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Ordinary shares, par value $0.001 per share |
| Trading Symbol | SW |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
