Legal Entity [Axis] Statements of Net Assets Available for Benefits [Abstract] Investment Type [Axis] Net Assets Available for Benefits Beginning of Year End of Year Statements of Changes in Net Assets Available for Benefits [Abstract] Total Contributions Net Increase In Net Assets Description of Plan [Abstract] Summary of Significant Accounting Policies [Abstract] Fair Value Measurements [Abstract] Fair Value Hierarchy and NAV [Axis] Plan Termination [Abstract] Tax Status [Abstract] Related Party Transactions [Abstract] Risks and Uncertainties [Abstract] Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract] Statistical Measurement [Axis] Document Type Document Period End Date Document Fiscal Year Focus Entity Registrant Name Entity Central Index Key Amendment Flag Assets Investments at Fair Value Investments at fair value Fair value (in Dollars) Notes Receivable from Participants Net Appreciation in Fair Value of Investments Interest and Dividends Interest on Notes Receivable from Participants Contributions Participants Rollovers Employer Net Assets Available for Benefits Benefits Paid to Participants Administrative Expenses MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] Money Market Funds [Member] Mutual Funds [Member] Common Collective Trusts [Member] Stock Fund [Member] Magnera Corporation Stock Fund [Member] Description of Plan Graded Vesting Schedule for Company Matching Contributions Vesting Percentage, Less than 2 years Vesting Percentage, 2 years Vesting Percentage, 3 years Vesting percentage, 3 years of service Vesting Percentage, 4 years Vesting Percentage, 5 or more years Summary of Significant Accounting Policies Fair Value Measurements Plan's Investments at Fair Value Plan Termination Tax Status Related Party Transactions Investments in Company Common Stock Through Stock Fund Shares or units (in Shares) Per-unit price (in Dollars per share) Risks and Uncertainties Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) Identity of Issuer, Borrower, Lessor, or Similar Party Current Value Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value Party-in-interest Participant Loans Participant Loans, interest rate Notes receivable from participants, interest rate Participant Loans, maturity date Notes receivable from participants, maturity year TOTAL Level 1 [Member] Magnera Corporation Common Stock [Member] Investment, Identifier [Axis] Participant Loans [Member] Minimum [Member] Maximum [Member] EBP, Contribution, Participating Employer [Axis] EBP, Participant-Directed and Nonparticipant-Directed Status [Axis] Receivable Type [Axis] Plan description available Employees minimum period of service to be eligible to participate in the Plan Treasure Holdco, Inc. 401(k) Plan related trust with assets merged with and into the Magnera 401(k) plan Maximum percentage of compensation each participant may contribute to the Plan Deferral rate of eligible compensation Minimum age participants will be eligible to make catch-up contributions (in Age) Maximum percentage of participants contributions that may be reallocated Replacement Suspense Account used Replacement Suspense Account Vesting term Vesting percentage, less than 3 years of service Amount of company contribution reduced from forfeited non-vested accounts Amount in forfeited non-vested accounts Participant vested account balance Minimum age participants may withdraw amounts due to hardship (in Age) Minimum amount participants may borrow from their vested account balance Maximum amount participants may borrow from their vested account balance Maximum percentage of vested account balance participants may borrow Notes receivable to participants, maximum percentage secured by the balances in the respective participants' accounts Notes receivable from participants, spread on prime rate Notes receivable from participants, minimum term Notes receivable from participants, maximum term Notes receivable from participants, maximum term Determination letter obtained Determination letter date EBP, Tax Qualification Status [Extensible Enumeration] Purchases made by the Plan for the investment in the Company’s common stock Sales made by the Plan for the investment in the Company’s common stock Plan Name Employer Idnetification Number Plan Number Basis of Presentation Use of Estimates Investments Payment of Benefits Investment Fees Subsequent Events Discretionary Contributions [Member] Fort Smith Group [Member] Participant Lump Sum Payment Upon Termination of Service Other Than by Retirement, Disability, or Death [Member] Distribution in Direct Rollover to an Individual Retirement Account Upon Termination of Service Other Than by Retirement, Disability, or Death - in the Absence of Specific Participant Direction [Member] Participant Assets May Remain in the Plan Upon Termination of Service Other Than by Retirement, Disability, or Death [Member] Notes Receivable Used for the Purchase of a Primary Residence [Member] Investments [Domain] Entity [Domain] EBP, Statement of Net Asset Available for Benefit [Table] Statements of Net Assets Available for Benefits [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Table] Statements of Changes in Net Assets Available for Benefits [Abstract] EBP, Description of Plan [Table] Description of Plan [Abstract] EBP, Accounting Policy [Table] Summary of Significant Accounting Policies [Abstract] EBP, Investment, Fair Value and NAV [Table] Fair Value Measurements [Abstract] Plan Termination [Abstract] EBP, Tax Status [Table] Tax Status [Abstract] EBP, Related Party and Party-in-Interest Transactions [Table] Related Party Transactions [Abstract] EBP, Risk and Uncertainty [Table] Risks and Uncertainties [Abstract] EBP, Schedule of Asset Held for Investment [Table] Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract] EBP, Accounting Policy [Line Items] Fair Value Hierarchy and NAV [Domain] Statistical Measurement [Domain] EBP, Contribution, Participating Employer [Domain] EBP, Participant-Directed and Nonparticipant-Directed Status [Domain] Receivable [Domain] Tabular disclosure of company matching contributions graded vesting schedule. Percentage of maximum secured account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow to total participant account balance. Percentage of participant compensation eligible for employer matching contribution, year five for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Percentage of participant compensation eligible for employer matching contribution, year four for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). The percentage of employer contribution vesting schedule less than three years of service. Percentage of participant compensation eligible for employer matching contribution, less than two years for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Percentage of employer contribution vesting schedule three years of service. Percentage of participant compensation eligible for employer matching contribution, year two for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Amount of replacement suspense account. The amount of employee benefit plan replacement suspense account was used to fund employer discretionary contributions. Disclosure of accounting policy for investment fees (employee benefit plan (EBP)). The minimum age participants may withdraw amounts due to hardship. Period of repayment of loan, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Period of repayment of loan, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Period of repayment of loan, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Maximum percentage of participants contributions that may be reallocated The age at which participants become eligible for contributions under employee benefit plan. Number of service days in employee stock purchase, saving, or similar plan (employee benefit plan (EBP). Amount of participant vested account balance. Period of repayment of loan, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Percentage points added to the reference rate to compute the variable rate on the notes receivable from participants. Mutual Fund [Member] Vanguard FTSE Social Index Fund Admiral [Member] Common Collective Trust [Member] Schwab Indexed Retirement Trust Fund 2020 [Member] Qualified Plan [Member] Common Stock [Member] Vanguard Extended Market Index Fund; Institutional Shares [Member] Diamond Hill Small-Mid Cap Fund; Y [Member] Goldman Sachs Small/Mid Cap Growth Fund; R6 [Member] Money Market [Member] Fidelity Intermediate Bond Fund [Member] Schwab Indexed Retirement Trust Fund 2060 [Member] Vanguard Equity Income Admiral Shares [Member] Vanguard Federal Money Market Fund [Member] Fidelity Puritan Fund; K [Member] Schwab Indexed Retirement Trust Fund 2025 [Member] Vanguard Total International Stock Index Fund [Member] Schwab Indexed Retirement Trust Fund 2035 [Member] Schwab Indexed Retirement Trust Fund 2040 [Member] Schwab Indexed Retirement Trust Fund 2050 [Member] Fidelity Large Cap Growth Index Fund [Member] Fidelity US Bond Index Fund [Member] Magnera Corporation [Member] Schwab Indexed Retirement Trust Fund 2030 [Member] Schwab Indexed Retirement Trust Fund 2055 [Member] Fidelity Government Money Market Fund Premium Class [Member] Fidelity 500 Index Fund [Member] Schwab Indexed Retirement Trust Fund 2045 [Member] EBP, Subsequent Event [Policy Text Block] EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant EBP, Employer, Common Stock Fund [Member] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] Notes Receivable Used For The Purchase Of APrimary Residence Member Employee Benefit Plan Minimum Age Participants May Withdraw Amounts Due To Hardship EBP, Employer, Common Stock [Member] EBP, Participant Contribution, Automatic, Deferral Rate Employee Benefit Plan Participant Minimum Age Eligible To Make Catch Up Contributions EBP, Tax Qualification Status [Extensible Enumeration] EBP, Plan Number Participant Loans Member EBP, Investment, Fair Value and NAV [Table Text Block] EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Distribution In Direct Rollover To An Individual Retirement Account Upon Termination Of Service Other Than By Retirement Disability Or Death In The Absence Of Specific Participant Direction Member Notes Receivable From Participants Basis Spread On Variable Rate EBP, Description, Available [true false] EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment EBP, Related Party and Party-in-Interest Transactions [Line Items] Employee Benefit Plan Investment Fees Policy Text Block Employee Benefit Plan Participant Maximum Contributions That May Be Reallocated Percentage Employee Benefit Plan Participant Vested Account Balance EBP, Asset Held for Investment, Participant Loan, Maturity Date Fair Value, Inputs, Level 1 [Member] EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense EBP, Summary of Accounting Policy [Text Block] EBP, Tax Status [Text Block] EBP, Note Receivable from Participant Employee Benefit Plan Note Receivable From Participant Account Maximum Borrowing Term Participant Assets May Remain In The Plan Upon Termination Of Service Other Than By Retirement Disability Or Death Member EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Discretionary Contributions Member Employee Benefit Plan Employer Replacement Suspense Account EBPNote Receivable From Participant Account Maximum Secured Amount To Total Account Percentage EBP, Change in Net Asset Available for Benefit, Increase from Contribution Employee Benefit Plan Employer Contribution Vesting Schedule Less Than Three Years Of Service Percentage EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount EBP, Related Party and Party-in-Interest Transactions [Table Text Block] EBP, Investment, Current Value, Type [Extensible Enumeration] EBP, Asset [Abstract] EBP, Use of Estimate [Policy Text Block] EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost EBP, Investment, Fair Value [Abstract] Employee Benefit Plan Employer Replacement Suspense Account Used EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution EBP, Description of Plan [Text Block] Employee Benefit Plan Employer Contribution Vesting Schedule Two Years Of Service Percentage Document Fiscal Year Focus Employee Benefit Plan Participant Minimum Period Of Service To Be Eligible To Participate In Plan Employee Benefit Plan Note Receivable From Participant Account Minimum Borrowing Term EBP, Tax Determination Letter, Date Employee Benefit Plan Employer Contribution Vesting Schedule Four Years Of Service Percentage EBP, Asset Held for Investment, Participant Loan, Interest Rate EBP017 Member EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Employee Benefit Plan Employer Contribution Vesting Schedule Five Or More Years Of Service Percentage EBP, Forfeited Nonvested Account Minimum [Member] EBP, Investment, Issuer Name [Extensible Enumeration] EBP, Plan Termination [Text Block] EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] EBP, Investment, Number of Shares EBP, Description of Plan [Line Items] EBP, Asset Held for Investment, Party-in-Interest [true false] EBP, Accounting Standard Update and Change in Accounting Principle [Line Items] EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash Company Matching Contributions Graded Vesting Schedule Table Text Block EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price EBP, Risk and Uncertainty [Text Block] EBP, Basis of Accounting [Policy Text Block] EBP, Investment, Fair Value and NAV [Line Items] EBP, Asset Held for Investment EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Net Asset Available for Benefit EBP, Investment [Policy Text Block] Maximum [Member] EBP, Schedule of Asset Held for Investment [Line Items] Document Type EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Entity Tax Identification Number Amendment Flag EBP, Tax Status [Line Items] Document Period End Date Employee Benefit Plan Employer Contribution Vesting Schedule Three Years Of Service Percentage EBP, Investment, Fair Value and NAV [Text Block] EBP, Schedule of Asset Held for Investment [Table Text Block] EBP, Risk and Uncertainty [Line Items] Entity Central Index Key EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Participant Lump Sum Payment Upon Termination Of Service Other Than By Retirement Disability Or Death Member Fort Smith Group Member Employee Benefit Plan Vesting Term EBP, Net Asset Value per Share or Unit Employee Benefit Plan Note Receivable From Participant Principal Residence Maximum Borrowing Term Investment, Identifier [Axis] EBP, Forfeited Nonvested Account, Decrease from Employer Contribution Employee Benefit Plan Employer Contribution Vesting Schedule Less Than Two Years Of Service Percentage EBP, Change in Net Asset Available for Benefit, Increase (Decrease) [Abstract] EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover EBP, Plan Name EBP, Payment to Participant [Policy Text Block] Entity Registrant Name EBP, Change in Net Asset Available for Benefit, Increase (Decrease) EBP, Tax Determination Letter, Obtained [true false]