| Cover Page and DEI Document | Mar. 31, 2021 |
| Document Information [Line Items] | |
| Entity Central Index Key | 0001739445 |
| Title of 12(b) Security | Common Stock ($0.01 par value) |
| Document Type | 8-K |
| Document Period End Date | Mar. 31, 2021 |
| Entity Registrant Name | Arcosa, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-38494 |
| Entity Tax Identification Number | 82-5339416 |
| Entity Address, Address Line One | 500 N. Akard Street, Suite 400 |
| Entity Address, City or Town | Dallas, |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75201 |
| City Area Code | 972 |
| Local Phone Number | 942-6500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Trading Symbol | ACA |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
