Document and Entity Information Document Information [Table] Legal Entity [Axis] Entity [Domain] Represents the Retirement Plan Number 003. E B P 003 [Member] Mayville Engineering Company, Inc. 401(k) Plan Document Information [Line Items] Document and Entity Information Document Type Entity Registrant Name Entity Tax Identification Number Entity tax identification number Entity Central Index Key Amendment Flag Statements of Net Assets Available for Benefits EBP, Statement of Net Asset Available for Benefit [Table] Investment Type [Axis] Investments [Domain] Mutual Fund [Member] Mutual funds EBP, Employer, Common Stock [Member] Corporate common stock Company stock EBP, Statement of Net Asset Available for Benefit [Line Items] Statements of Net Assets Available for Benefits EBP, Asset [Abstract] Assets: EBP, Investment, Fair Value [Abstract] Investments at fair value: EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Investments at fair value EBP, Net Asset Available for Benefit Net assets available for benefits, End of year Net assets available for benefits, Beginning of year Net assets available for benefits Statement of Changes in Net Assets Available for Benefits EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] Statement of Changes in Net Assets Available for Benefits EBP, Change in Net Asset Available for Benefit, Increase (Decrease) [Abstract] Changes in Net Assets Available for Benefits EBP, Change in Net Asset Available for Benefit, Increase [Abstract] Additions: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Interest and dividends EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment Total investment income EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Participants EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash Company EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Rollovers EBP, Change in Net Asset Available for Benefit, Increase from Contribution Total contributions EBP, Change in Net Asset Available for Benefit, Increase Total additions EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Deductions: EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease Total deductions EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Net increase before transfers EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan Plan transfers Plan transfers (see Note 4) Amount of increase (decrease) after transfers from plan in net asset available for benefit to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan Change In Net Asset Available For Benefit Increase Decrease After Transfers From Plan Net increase after transfers Description of Plan EBP, Description of Plan [Table] EBP, Description of Plan [Line Items] Description of Plan EBP, Description of Plan [Text Block] Description of Plan Summary of Significant Accounting Policies EBP, Accounting Policy [Table] EBP, Accounting Policy [Line Items] Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Summary of Significant Accounting Policies No definition available. Plan Termination EBP, Plan Termination [Text Block] Plan Termination No definition available. Plan Transfers Disclosure of information about plan transfers in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan, Plan Transfer [Table] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Employee Benefit Plan, Plan Transfer [Line Items] Plan Transfers The entire disclosure of plan transfers in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan, Plan Transfer [Text Block] Plan Transfers Fair Value Measurements EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Line Items] Fair Value Measurements EBP, Investment, Fair Value and NAV [Text Block] Fair Value Measurements Tax Status EBP, Tax Status [Table] EBP, Tax Status [Line Items] Tax Status EBP, Tax Status [Text Block] Tax Status Party-in-Interest and Related Party Transactions EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Line Items] Party-in-Interest and Related Party Transactions EBP, Related Party and Party-in-Interest Transactions [Text Block] Party-in-Interest and Related Party Transactions Risks and Uncertainties EBP, Risk and Uncertainty [Table] EBP, Risk and Uncertainty [Line Items] Risks and Uncertainties EBP, Risk and Uncertainty [Text Block] Risks and Uncertainties Schedule of Assets EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Line Items] Schedule of Assets EBP, Schedule of Asset Held for Investment [Text Block] Schedule of Assets EBP, Basis of Accounting [Policy Text Block] Basis of Accounting Disclosure of accounting policy for income recognition and investment valuation held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan, Investment Valuation and Income Recognition [Policy Text Block] Investment Valuation and Income Recognition EBP, Use of Estimate [Policy Text Block] Use of Estimates EBP, Expense [Policy Text Block] Expenses EBP, Payment to Participant [Policy Text Block] Payments of Benefits EBP, Subsequent Event [Policy Text Block] Subsequent Events Tabular disclosure of plan transfers in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan, Plan Transfer [Table Text Block] Schedule of plan transfers EBP, Investment, Fair Value and NAV [Table Text Block] Schedule of the Plan's assets at fair value Statistical Measurement [Axis] Statistical Measurement [Domain] Maximum [Member] Maximum Represents the minimum service period for discretionary contribution in employee benefit plan (EBP). Employee Benefit Plan, Minimum Service Period For Discretionary Contribution Eligibility Minimum service period for profit sharing contribution eligibility (in hours) EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Participant's contribution Age specified by the employee benefit plan at which participants become eligible to make catch-up contributions under applicable plan provisions and statutory requirements. Employee Benefit Plan,. Catch-up Contribution Eligibility Age Age for contribution eligibility EBP, Participant Contribution, Automatic, Deferral Rate Deferral rate Percentage of annual increase in deferral rate in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan Participant Contribution Deferral Rate, Annual Increase Auto-escalation of contribution rates EBP, Employer Contribution, Matching Percentage Matching contributions EBP, Employer Contribution, Participant Compensation Matched, Percentage Percentage of matching contribution EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Noncash Discretionary contributions Represents the percentage of vesting. Employee Benefit Plan, Vesting Percentage Vesting percentage Represents the period of vesting for discretionary contribution. Employee Benefit Plan, Discretionary Contribution, Vesting Period Vesting period Represent the percentage of vesting in case of plan termination. Employee Benefit Plan, Plan Termination, Vesting Percentage Vesting percentage during termination Threshold balance of participant account below which amount automatically distributed as lumpsum amount immediately in Employee benefit plan. Employee Benefit Plan, Automatic Distribution, Threshold Amount Threshold participant vested balance EBP, Forfeited Nonvested Account Forfeited nonvested accounts EBP, Forfeited Nonvested Account, Reallocated to Participant Forfeited accounts allocated to participants Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event Percentage of equity interest acquired by employer in business combination. Employee Benefit Plan Business Combination Acquisition Percentage By Employer Acquisition percentage Represents the minimum service period for plan transfer eligibility under (employee benefit plan (EBP)). Employee Benefit Plan, Minimum Service Period For Plan Transfer Eligibility Minimum age for plan transfer eligibility Represents the minimum service period for plan transfer eligibility under (employee benefit plan (EBP)). Employee Benefit Plan, Minimum Age For Plan Transfer Eligibility Minimum service period for plan transfer eligibility Percentage of balance in ESOP plan eligible for transfer to this plan. Employee Benefit Plan, Percentage of ESOP Balance Eligible To Transfer Percentage of ESOP balance to transfer Period within which plan transfer can be done under (employee benefit plan (EBP)). Employee Benefit Plan, Initial Plan Transfer Period Plan transfer period Additional Percentage of balance in ESOP plan eligible for transfer to this plan. Employee Benefit Plan, Additional Percentage of ESOP Balance Eligible To Transfer Additional percentage of ESOP balance to transfer Amount of increase in net asset available for benefit from contribution transferred from ESOP plan of participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan Change In Net Asset Available For Benefit Increase For Participant Contribution Rollover From ESOP Plan Rollovers from employee stock ownership plan Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 [Member] Level 1 EBP, Tax Determination Letter, Obtained [true false] Determination letter obtained EBP, Tax Determination Letter, Date Determination letter date EBP, Tax Qualification Status [Extensible Enumeration] Tax qualification status EBP, Related Party and Party-in-Interest [Axis] EBP, Related Party and Party-in-Interest [Domain] EBP, Trustee [Member] Principal Financial Group Employer of participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Employee Benefit Plan, Employer [Member] Employer EBP, Investment, Number of Shares Shares held EBP, Investment, Excluding Plan Interest in Master Trust, Cost Shares held at cost EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost Value of shares acquired EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price Proceeds from sale of shares EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Realized Gain (Loss) on Investment Realized gain Investment, Identifier [Axis] EBP, Plan Number Plan number EBP, Asset Held for Investment, Party-in-Interest [true false] EBP, Asset Held for Investment, Party-in-Interest [true false] EBP, Investment, Issuer Name [Extensible Enumeration] EBP, Investment, Issuer Name [Extensible Enumeration] EBP, Investment, Current Value, Type [Extensible Enumeration] EBP, Investment, Current Value, Type [Extensible Enumeration] EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Current Value