v3.26.1
Cover - USD ($)
 12 Months Ended
Dec. 31, 2025
Apr. 29, 2026
Cover [Abstract]    
Document Type 10-K/A  
Amendment Flag true  
Document Period End Date Dec. 31, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus FY  
Entity Registrant Name TCW Steel City Senior Lending BDC  
Entity Central Index Key 0002043133  
Current Fiscal Year End Date --12-31  
Entity Well-known Seasoned Issuer No  
Entity Current Reporting Status Yes  
Entity Voluntary Filers No  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   12,093,673
Entity Public Float $ 0  
Entity File Number 000-56771  
Entity Tax Identification Number 33-1515587  
Entity Address, Address Line One 200 Clarendon Street  
Entity Address, City or Town Boston  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 02116  
City Area Code 617  
Local Phone Number 936-2275  
Entity Interactive Data Current Yes  
Entity Incorporation, State or Country Code DE  
Document Annual Report true  
Document Transition Report false  
Document Financial Statement Error Correction [Flag] false  
ICFR Auditor Attestation Flag false  
Documents Incorporated by Reference [Text Block] None.  
Amendment Description EXPLANATORY NOTE TCW Steel City Senior Lending BDC (the “Company”) is filing this Amendment No. 1 on Form 10-K/A (the “Amendment”) to the Company’s annual report on Form 10-K for the year ended December 31, 2025 (the “Form 10-K”), filed with the Securities and Exchange Commission on March 26, 2026 (the “Original Filing”). The Company is filing this Amendment to include the information required by Items 10 through 14 of Part III of Form 10-K that was previously omitted from the Original Filing. Except as set forth in this Amendment, no other changes have been made to the Form 10-K.  
Auditor Name Deloitte & Touche LLP  
Auditor Firm ID 34  
Auditor Location Los Angeles, California, United States of America  
Entity Ex Transition Period false