v3.25.1
Cover - shares
 3 Months Ended
Mar. 31, 2025
Jun. 13, 2025
Document Type 10-Q  
Amendment Flag false  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Mar. 31, 2025  
Document Fiscal Period Focus Q1  
Document Fiscal Year Focus 2025  
Current Fiscal Year End Date --12-31  
Entity File Number 001-42196  
Entity Registrant Name Copley Acquisition Corp  
Entity Central Index Key 0002045473  
Entity Tax Identification Number 00-0000000  
Entity Incorporation, State or Country Code E9  
Entity Address, Address Line One Suite 4005-4006, 40/F  
Entity Address, Address Line Two One Exchange Square  
Entity Address, Address Line Three 8 Connaught Place  
Entity Address, City or Town Central  
Entity Address, Country HK  
Entity Address, Postal Zip Code 00000  
City Area Code +852  
Local Phone Number 2861 3335  
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  
Elected Not To Use the Extended Transition Period false  
Entity Shell Company true  
Units, each consisting of one Class A ordinary share and one-half of one redeemable warrant    
Title of 12(b) Security Units, each consisting of one Class A ordinary share and one-half of one redeemable warrant  
Trading Symbol COPLU  
Security Exchange Name NYSE  
Class A ordinary shares, par value $0.0001 per share    
Title of 12(b) Security Class A ordinary shares, par value $0.0001 per share  
Trading Symbol COPL  
Security Exchange Name NYSE  
Warrants, each whole warrant entitles the holder thereof to purchase one Class A ordinary share at a price of $11.50 per share    
Title of 12(b) Security Warrants, each whole warrant entitles the holder thereof to purchase one Class A ordinary share at a price of $11.50 per share  
Trading Symbol COPLW  
Security Exchange Name NYSE  
Common Classs A [Member]    
Entity Common Stock, Shares Outstanding   17,422,500
Commons Class B [Member]    
Entity Common Stock, Shares Outstanding   5,750,000