| Cover Page | Feb. 25, 2020 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Feb. 25, 2020 |
| Entity Registrant Name | ADVANSIX INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-37774 |
| Entity Tax Identification Number | 81-2525089 |
| Entity Address, Address Line One | 300 Kimball Drive |
| Entity Address, Address Line Two | Suite 101 |
| Entity Address, City or Town | Parsippany |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07054 |
| City Area Code | 973 |
| Local Phone Number | 526-1800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | ASIX |
| Security Exchange Name | NYSE |
| Amendment Flag | false |
| Entity Central Index Key | 0001673985 |
