v3.25.2
Cover - shares
 6 Months Ended
Jun. 30, 2025
Aug. 12, 2025
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 Jun. 30, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Entity Information [Line Items]    
Entity Registrant Name HCM II ACQUISITION CORP.  
Entity Central Index Key 0002019804  
Entity File Number 001-42252  
Entity Tax Identification Number 98-1785406  
Entity Incorporation, State or Country Code E9  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status No  
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 Contact Personnel [Line Items]    
Entity Address, Address Line One 100 First Stamford Place  
Entity Address, Address Line Two Suite 330  
Entity Address, City or Town Stamford  
Entity Address, State or Province CT  
Entity Address, Postal Zip Code 06902  
Entity Phone Fax Numbers [Line Items]    
City Area Code (203)  
Local Phone Number 930-2200  
Units, each consisting of one Class A ordinary share and one-half of one Redeemable Warrant    
Entity Listings [Line Items]    
Title of 12(b) Security Units, each consisting of one Class A ordinary share and one-half of one Redeemable Warrant  
Trading Symbol HONDU  
Security Exchange Name NASDAQ  
Class A Ordinary Shares, par value $0.0001 per share    
Entity Listings [Line Items]    
Title of 12(b) Security Class A Ordinary Shares, par value $0.0001 per share  
Trading Symbol HOND  
Security Exchange Name NASDAQ  
Redeemable Warrants, each whole warrant exercisable for one Class A ordinary share at a price of $11.50 per share    
Entity Listings [Line Items]    
Title of 12(b) Security Redeemable Warrants, each whole warrant exercisable for one Class A ordinary share at a price of $11.50 per share  
Trading Symbol HONDW  
Security Exchange Name NASDAQ  
Class A Ordinary Shares    
Entity Listings [Line Items]    
Entity Common Stock, Shares Outstanding   23,000,000
Class B Ordinary Shares    
Entity Listings [Line Items]    
Entity Common Stock, Shares Outstanding   5,750,000