v3.25.2
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2025
Aug. 11, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2025  
Entity File Number 001-37990  
Entity Registrant Name LEAP THERAPEUTICS, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 27-4412575  
Entity Address, Address Line One 47 Thorndike St, Suite B1-1  
Entity Address, City or Town Cambridge  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 02141  
City Area Code 617  
Local Phone Number 714-0360  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol LPTX  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   41,439,529
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0001509745  
Amendment Flag false