| Document and Entity Information | Feb. 25, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | PACKAGING CORP OF AMERICA |
| Amendment Flag | false |
| Entity Central Index Key | 0000075677 |
| Document Type | 8-K |
| Document Period End Date | Feb. 25, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-15399 |
| Entity Tax Identification Number | 36-4277050 |
| Entity Address, Address Line One | 1 N. Field Court |
| Entity Address, City or Town | Lake Forest |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60045 |
| City Area Code | (847) |
| Local Phone Number | 482-3000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock |
| Trading Symbol | PKG |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
