v3.25.1
Organization and Summary of Significant Accounting Policies - Additional Information (Detail)
 1 Months Ended 3 Months Ended
Mar. 31, 2025
USD ($)
$ / shares
Jan. 01, 2010
USD ($)
Mar. 31, 2025
USD ($)
$ / shares
Mar. 31, 2025
USD ($)
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    
Top 50 Songs in the Catalogue       EMI has provided the Trust with a listing of the top 50 earning songs in the Catalogue during the 2024 calendar year (the “Top 50 Songs”), together with certain copyright information with respect to each of the Top 50 Songs (the “Listing”). A copy of the Listing, as provided by EMI, is included in the Trust’s annual report on Form 10-K for the fiscal year ended December 31, 2024. The Listing does not include any information regarding Copyrighted Songs for the 2025 calendar year.
Proceeds from Royalties Received     $ 260,759  
Amount Paid To Third Party     196,827  
Reserve fund for potential future expenses which have not yet been incurred $ 63,932   $ 63,932 $ 63,932
Cash held in reserve per trust unit | $ / shares $ 0.2302      
Receipts from EMI per trust unit | $ / shares     $ 0.9390  
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%    
Top 50 Song Listing [Member]        
Organization And Summary Of Significant Accounting Policies [Line Items]        
Top 50 Songs in the Catalogue       50
Estimated number of songs in the Catalogue       12,000
Estimated number of songs producing royalty income       1,430