Document And Entity Information |
12 Months Ended |
|---|---|
Dec. 31, 2025 | |
| Document Information Line Items | |
| Entity Central Index Key | 0000041719 |
| Document Type | 11-K |
| Document Period End Date | Dec. 31, 2025 |
| Document Fiscal Year Focus | 2025 |
| Entity Registrant Name | MAGNERA CORPORATION |
| Amendment Flag | false |
| MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] | |
| Document Information Line Items | |
| Document Type | 11-K |
| Document Period End Date | Dec. 31, 2025 |
| Document Fiscal Year Focus | 2025 |
| Amendment Flag | false |