v3.26.1
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Aug. 12, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-42214  
Entity Registrant Name SILVERBOX CORP IV  
Entity Incorporation, State or Country Code E9  
Entity Tax Identification Number 00-0000000  
Entity Address, Address Line One 8701 Bee Cave Road  
Entity Address, Adress Line Two East Building, Suite 310  
Entity Address, City or Town Austin  
Entity Address State Or Province TX  
Entity Address, Postal Zip Code 78746  
City Area Code 512  
Local Phone Number 575-3637  
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  
Entity Shell Company true  
Entity Central Index Key 0002015947  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false  
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 Class A ordinary share, $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, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50  
Trading Symbol SBXD WS  
Security Exchange Name NYSE  
Class A ordinary shares    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   6,422,333
Class B ordinary shares    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   1