Basis of Presentation	9 Months Ended
Jun. 27, 2026
Basis of Presentation [Abstract]
Basis of Presentation	1. Basis of Presentation On November 4, 2024 (the “Closing Date”), Treasure Holdco, Inc., a wholly owned subsidiary of Berry Global Group, Inc. (“Berry”), completed its merger (the “merger”) with the Glatfelter Corporation which concurrently changed its name to Magnera Corporation ("Magnera" or the "Company"). The Condensed Consolidated and Combined Financial Statements contain combined financial statements for the fiscal periods prior to the Closing Date of the merger and were prepared on a stand-alone basis. The pre-merger Combined Financial Statements of Operations, Comprehensive Income (Loss), Cash Flows and Changes in Equity have been prepared on a carve-out basis, which include assumptions underlying the preparation that management believes are reasonable. However, the combined pre-merger financial information included herein may not necessarily reflect the Company’s results of operations, comprehensive income (loss), cash flows and changes in equity had the Company been an independent stand-alone company during the periods presented. The accompanying unaudited Condensed Consolidated and Combined Financial Statements of Magnera have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim reporting. In preparing financial statements in conformity with GAAP, we must make estimates and assumptions that affect the reported amounts and disclosures at the date of the financial statements and during the reporting period. Actual results could differ from those estimates. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included, and all subsequent events up to the time of the filing have been evaluated. For further information, refer to the Company’s Form 10-K filed with the SEC on November 25, 2025. Recently Issued Accounting Pronouncements In 2023, the Financial Accounting Standards Board ("FASB") issued guidance with the goal of providing more information in the income tax reconciliation table and regarding income taxes paid. This Accounting Standard Update ("ASU") is effective for fiscal years beginning after December 15, 2024, may be applied prospectively or retrospectively, and allows for early adoption. The Company is currently evaluating the impact of adopting this guidance, which will be effective for the fiscal year ending September 26, 2026. In 2024, the FASB issued guidance with the goal of providing more expense information for certain categories of expenses that are included in line items on the face of the statements of operations. This ASU is effective for fiscal years beginning after December 15, 2026 and for interim periods beginning after December 15, 2027, may be adopted on a prospective or retrospective basis, and allows for early adoption. The Company is currently evaluating the impact of adopting this guidance.

On November 4, 2024 (the “Closing Date”), Treasure Holdco, Inc., a wholly owned subsidiary of Berry Global Group, Inc. (“Berry”), completed its merger (the “merger”) with the Glatfelter Corporation which concurrently changed its name to Magnera Corporation ("Magnera" or the "Company").

The Condensed Consolidated and Combined Financial Statements contain combined financial statements for the fiscal periods prior to the Closing Date of the merger and were prepared on a stand-alone basis. The pre-merger Combined Financial Statements of Operations, Comprehensive Income (Loss), Cash Flows and Changes in Equity have been prepared on a carve-out basis, which include assumptions underlying the preparation that management believes are reasonable. However, the combined pre-merger financial information included herein may not necessarily reflect the Company’s results of operations, comprehensive income (loss), cash flows and changes in equity had the Company been an independent stand-alone company during the periods presented.

The accompanying unaudited Condensed Consolidated and Combined Financial Statements of Magnera have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim reporting. In preparing financial statements in conformity with GAAP, we must make estimates and assumptions that affect the reported amounts and disclosures at the date of the financial statements and during the reporting period. Actual results could differ from those estimates. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included, and all subsequent events up to the time of the filing have been evaluated. For further information, refer to the Company’s Form 10-K filed with the SEC on November 25, 2025.

In 2023, the Financial Accounting Standards Board ("FASB") issued guidance with the goal of providing more information in the income tax reconciliation table and regarding income taxes paid. This Accounting Standard Update ("ASU") is effective for fiscal years beginning after December 15, 2024, may be applied prospectively or retrospectively, and allows for early adoption. The Company is currently evaluating the impact of adopting this guidance, which will be effective for the fiscal year ending September 26, 2026.

In 2024, the FASB issued guidance with the goal of providing more expense information for certain categories of expenses that are included in line items on the face of the statements of operations. This ASU is effective for fiscal years beginning after December 15, 2026 and for interim periods beginning after December 15, 2027, may be adopted on a prospective or retrospective basis, and allows for early adoption. The Company is currently evaluating the impact of adopting this guidance.