v3.26.1
Document And Entity Information - shares
 3 Months Ended
Mar. 31, 2026
Apr. 30, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Transition Report false  
Entity File Number 001-39696  
Entity Registrant Name COMPASS THERAPEUTICS, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 82-4876496  
Entity Address, Address Line One 80 Guest St., Suite 601  
Entity Address, City or Town Boston  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 02135  
City Area Code 617  
Local Phone Number 500-8099  
Title of 12(b) Security Common Stock, $0.0001 par value per share  
Trading Symbol CMPX  
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 (in shares)   180,087,915
Entity Central Index Key 0001738021  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Amendment Flag false