v3.26.1
Cover - shares
 3 Months Ended
Mar. 31, 2026
May 08, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Entity Interactive Data Current Yes  
Amendment Flag false  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Entity Registrant Name FACT II ACQUISITION CORP.  
Entity Central Index Key 0002028935  
Entity File Number 001-42421  
Entity Tax Identification Number 00-0000000  
Entity Incorporation, State or Country Code E9  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Shell Company true  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Address, Address Line One 14 Wall Street  
Entity Address, Address Line Two 20th Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10005  
City Area Code (212)  
Local Phone Number 618-1798  
Units, each consisting of one Class A ordinary share, par value $0.0001 per share, and one-half of one redeemable warrant    
Document Information [Line Items]    
Title of 12(b) Security Units, each consisting of one Class A ordinary share, par value $0.0001 per share, and one-half of one redeemable warrant  
Trading Symbol FACTU  
Security Exchange Name NASDAQ  
Class A ordinary shares, par value $0.0001 per share, included as part of the units    
Document Information [Line Items]    
Title of 12(b) Security Class A ordinary shares, par value $0.0001 per share, included as part of the units  
Trading Symbol FACT  
Security Exchange Name NASDAQ  
Warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50    
Document Information [Line Items]    
Title of 12(b) Security 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 FACTW  
Security Exchange Name NASDAQ  
Class A Ordinary Shares    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   18,488,125
Class B Ordinary Shares    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   5,833,333