v3.26.1
Accounting Policies and General Information - Additional Information (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2010
Dec. 31, 2025
Dec. 31, 2024
Mar. 31, 2026
Nov. 05, 2025
Organization And Summary Of Significant Accounting Policies [Line Items]          
Date of formation of Mills Music Trust   Dec. 03, 1964      
Minimum payment of quarterly Contingent Portion $ 167,500        
Receipts from EMI   $ 1,570,141 [1] $ 1,291,775    
Cash Distributions to Unit Holders   $ 652,817 [2] $ 658,733    
Distributions per Unit   $ 2.35 $ 2.37    
Unpaid administrative expenses for services     $ 0 $ 0  
Amount Of Payment To The Trust   $ 500,000     $ 500,000
Maximum Percentage Deduction By EMI on Foreign Affiliate Sub-Publishing Fees   25.00%      
Minimum [Member]          
Organization And Summary Of Significant Accounting Policies [Line Items]          
Percentage of Contingent Portion of gross royalty income 65.00%        
Maximum [Member]          
Organization And Summary Of Significant Accounting Policies [Line Items]          
Percentage of Contingent Portion of gross royalty income 75.00%        
[1] The proceeds received by the Trust for the year ended December 31, 2025 include the Settlement Payment in the amount of $500,000. For further information see “Recent Audit Settlement” under Part II, Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations”.
[2] The Trust did not make any distributions to Unit Holders in the first, second or third quarter of 2025. Instead, all payments of the Contingent Portion received by the Trust in respect of such periods were held in reserve by the Trust for future potential administrative expenses and liabilities in accordance with the Declaration of Trust. The full balance of the reserve, in the aggregate amount of $377,109, less any unpaid invoices from advisors and professionals providing services to the Trust and for administrative costs associated with the Trust, was distributed to Unit Holders in Q4 2025.