v3.26.1
Cover - shares
 3 Months Ended
Mar. 31, 2026
May 13, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Entity Registrant Name MERLIN, INC.  
Document Transition Report false  
Amendment Flag false  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Entity Central Index Key 0002028707  
Entity File Number 001-42392  
Entity Tax Identification Number 98-1797826  
Entity Incorporation, State or Country Code DE  
Current Fiscal Year End Date --12-31  
Entity Interactive Data Current Yes  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Address, Address Line One 100 Causeway, Floor 23  
Entity Address, City or Town Boston  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 02114  
City Area Code (617)  
Local Phone Number 226-9968  
Title of 12(b) Security Common Stock, par value $0.0001 per share  
Trading Symbol MRLN  
Security Exchange Name NASDAQ  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   96,524,052