v3.26.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2025
Mar. 19, 2026
Document and Entity Information    
Document Type 10-K  
Document Annual Report true  
Document Transition Report false  
Document Period End Date Dec. 31, 2025  
Entity File Number 001-41632  
Entity Registrant Name SilverBox Corp IV  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 00-0000000  
Entity Address State Or Province TX  
Entity Address, Address Line One 8701 Bee Cave Road, East  
Entity Address, Adress Line Two Building, Suite 310  
Entity Address, City or Town Austin  
Entity Address, Postal Zip Code 78746  
City Area Code 512  
Local Phone Number 575-3637  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
ICFR Auditor Attestation Flag false  
Document Financial Statement Error Correction [Flag] false  
Entity Shell Company true  
Entity Public Float $ 216,413,900  
Entity Central Index Key 0002015947  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus FY  
Amendment Flag false  
Transition Report false  
Auditor Name WithumSmith+Brown, PC  
Auditor Location New York, New York  
Auditor Firm ID 100  
Units, each consisting of one share of Class A ordinary shares, $0.0001 par value, and one-third of one redeemable warrant    
Document and Entity Information    
Title of 12(b) Security Units, each consisting of one share of Class A ordinary shares, $0.0001 par value, and one-third of one redeemable warrant  
Trading Symbol SBXDU  
Security Exchange Name NYSE  
Class A ordinary shares, par value $0.0001 per share    
Document and Entity Information    
Title of 12(b) Security Class A ordinary shares, par value $0.0001 per share  
Trading Symbol SBXD  
Security Exchange Name NYSE  
Redeemable warrants included as part of the units, each whole warrant exercisable for one share of Class A ordinary shares at an exercise price of $11.50 per share    
Document and Entity Information    
Title of 12(b) Security Redeemable warrants included as part of the units  
Trading Symbol SBXD WS  
Security Exchange Name NYSE  
Class A ordinary shares    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   20,455,000
Class B ordinary shares    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   5,000,000