1001 - Document - Cover Page link:presentationLink link:definitionLink link:calculationLink 1002 - Statement - Statements of Cash Receipts and Disbursements link:presentationLink link:definitionLink link:calculationLink 1003 - Statement - Statements of Cash Receipts and Disbursements (Parenthetical) link:presentationLink link:definitionLink link:calculationLink 999001 - Disclosure - Organization and Summary of Significant Accounting Policies link:presentationLink link:definitionLink link:calculationLink 999002 - Disclosure - Income Taxes link:presentationLink link:definitionLink link:calculationLink 999003 - Disclosure - Governance of the Trust link:presentationLink link:definitionLink link:calculationLink 999004 - Disclosure - Related Party Transactions link:presentationLink link:definitionLink link:calculationLink 999005 - Disclosure - Segment Information link:presentationLink link:definitionLink link:calculationLink 999006 - Disclosure - Subsequent Events link:presentationLink link:definitionLink link:calculationLink 999007 - Disclosure - Organization and Summary of Significant Accounting Policies (Policies) link:presentationLink link:definitionLink link:calculationLink 999008 - Disclosure - Organization and Summary of Significant Accounting Policies (Tables) link:presentationLink link:definitionLink link:calculationLink 999009 - Disclosure - Related Party Transactions (Tables) link:presentationLink link:definitionLink link:calculationLink 999010 - Disclosure - Organization and Summary of Significant Accounting Policies - Additional Information (Detail) link:presentationLink link:definitionLink link:calculationLink 999011 - Disclosure - Organization and Summary of Significant Accounting Policies - Schedule of Contingent Portion Payments (Detail) link:presentationLink link:definitionLink link:calculationLink 999012 - Disclosure - Income Taxes - Additional Information (Detail) link:presentationLink link:definitionLink link:calculationLink 999013 - Disclosure - Related Party Transactions - Additional Information (Detail) link:presentationLink link:definitionLink link:calculationLink 999014 - Disclosure - Related Party Transactions - Disbursements to Trustees (Detail) link:presentationLink link:definitionLink link:calculationLink Cover [Abstract] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Shell Company Entity Shell Company Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity File Number City Area Code Local Phone Number Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line Two Entity Address, City or Town Entity Address, Postal Zip Code Entity Address, State or Province Document Transition Report Document Quarterly Report Operating Cash Flows, Direct Method [Abstract] Proceeds From Contingent Portion Payments Receipts from EMI Proceeds from Contingent Portion payments attributable to royalty income generated by the Catalogue. Cash Undistributed Cash at Beginning of Period Undistributed Cash at End of Period General And Administrative Cash Outflow Disbursements—Administrative Expenses General and administrative cash outflow. Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Balance Available for Distribution Cash Distributions To Unit Holders Cash Distributions to Unit Holders Distributions to Unit Holders Cash distributions to Unit Holders. Cash Distribution Per Unit Cash Distributions Per Unit (based on 277,712 Trust Units Outstanding) Cash distribution per Trust Unit based on number Trust Units outstanding. Statement [Table] Statement [Line Items] Number Of Common Units Outstanding Number of Trust Units Outstanding Number of Trust Units Outstanding. Reserve fund for potential future expenses which have not yet been incurred Reserve fund for potential future expenses which have not yet been incurred Reserve fund for potential future expenses which have not yet been incurred. Receipts from EMI per trust unit Receipts from EMI per trust unit Distribution to Unit Holders per trust unit Receipts from EMI per trust unit. Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Related Party Transaction [Axis] Related Party Transaction [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Asset Class [Axis] Asset Class [Domain] Asset, Held-in-Trust [Member] Transactions [Axis] Transactions [Domain] Additional Q4 Amount [Member] Additional Q4 Amount [Member] Accounting Policies [Abstract] Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Organization and Summary of Significant Accounting Policies Income Tax Disclosure [Abstract] Income Tax Disclosure [Text Block] Income Taxes Business Combinations [Abstract] Governance Of Trust Disclosure TextBlock Governance of the Trust Disclosure about Governance of Trust. Related Party Transactions [Abstract] Related Party Transactions Disclosure [Text Block] Related Party Transactions Segment Reporting [Abstract] Segment Reporting Disclosure [Text Block] Segment Information Subsequent Events [Abstract] Subsequent Events [Text Block] Subsequent Events Organization And Background [Policy Text Block] Organization and Background Organization and background. Proceeds From Contingent Portion Payments Policy [Policy Text Block] Proceeds from Contingent Portion Payments Proceeds from Contingent Portion Payments. Cash Distributions To Unit Holders Policy [Policy Text Block] Cash Distributions to Unit Holders Cash distributions to Unit Holders. Basis of Accounting, Policy [Policy Text Block] Accounting Policies Calculation Of Contingent Portion Policy TextBlock Calculation of Contingent Portion Calculation of contingent portion. Copyright Catalogue Information Policy TextBlock The Copyright Catalogue Information regarding the Copyright Catalogue. New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Schedule of Deficiency for Contingent Consideration [Table Text Block] Schedule of Contingent Portion Payments Schedule of Deficiency for Contingent Consideration Table [Text Block] Schedule of Related Party Transactions [Table Text Block] Disbursements to Trustees Organization And Summary Of Significant Accounting Policies [Table] Organization And Summary Of Significant Accounting Policies [Table] Organization And Summary Of Significant Accounting Policies [Table] Organization And Summary Of Significant Accounting Policies [Line Items] Organization And Summary Of Significant Accounting Policies [Line Items] Organization And Summary Of Significant Accounting Policies [Line Items] Entity Incorporation, Date of Incorporation Date of formation of Mills Music Trust Contingent Portion Payable Equal To Gross Royalty Income Percent Percentage of Contingent Portion of gross royalty income Calculation percentage for Contingent Portion formula. Minimum Payment Of Quarterly Contingent Portion Minimum payment of quarterly Contingent Portion Minimum payment of quarterly contingent portion. Songs Listed In Catalogue For Top Earnings Top 50 Songs in the Catalogue Songs listed in Catalogue for top earnings. Estimated Number Of Songs In Catalogue Estimated number of songs in the Catalogue Estimated number of songs in the Catalogue. Estimated Number of Songs Producing Royalty Income Estimated number of songs producing royalty income Estimated number of songs producing royalty income. Amount Paid To Third Party Disbursements - Administrative Expenses Amount paid to third party. Proceeds from Royalties Received Receipts from EMI Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Top 50 Song Listing [Member] Top 50 song listing. Litigation Status [Axis] Litigation Status [Domain] Q4 Contingent Portion Payment [Member] Q4 Contingent Portion Payment [Member] Q3 Tru Up Payment [Member] Q3 Tru Up Payment [Member] Unit Holders [Member] Amount Of Deficiency For Contingent Consideration Deficiency in Contingent Portion payments Amount of deficiency for contingent consideration portion payments. Income Tax Expense (Benefit) Provision for income taxes Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Trustee Fees Trustee Annual Compensation Trustee annual compensation Amount of annual compensation for each Trustee's services, provided that such aggregate compensation to the Trustees as a group may not exceed a certain percentage of the Contingent Portion Payments received by the Trust in any year. Aggregate Compensation Percentage To Trustee Aggregate compensation percentage to Trustees Percentage of Contingent Portion Payments received by the Trust in any year which may not be exceeded as an amount of aggregate compensation to the Trustees as a group. Expense Charged Or Paid Trust For Office SpaceAnd Office Equipment Expenses charged or paid Trust for office space and office equipment Additional expenses being charged or paid by the Trust to the Trustee for office space and office equipment being utilized by the Trust. Legal Entity of Counterparty, Type [Axis] Legal Entity of Counterparty, Type [Axis] Legal Entity Type of Counterparty [Domain] Legal Entity Type of Counterparty [Domain] Individual Counterparty [Member] Individual Trustee Fees [Member] Trustee Fees Trustee Fees and Expenses Corporate Trustee Fees [Member] Corporate Trustee Fees [Member] Corporate Trustee Fees. Transfer Agent Registrar Fees [Member] Transfer Agent Registrar Fees [Member]