| Cover | 9 Months Ended |
| Sep. 30, 2020 | |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 3, 2020 |
| Entity Registrant Name | CLEARWATER PAPER CORPORATION |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-34146 |
| Entity Tax Identification Number | 20-3594554 |
| Entity Address, Address Line One | 601 West Riverside, |
| Entity Address, Address Line Two | Suite 1100 |
| Entity Address, Postal Zip Code | 99201 |
| Entity Address, State or Province | WA |
| Entity Address, City or Town | Spokane, |
| City Area Code | 509 |
| Local Phone Number | 344-5900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | CLW |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001441236 |
| Amendment Flag | false |
