v3.10.0.1
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2018
Nov. 01, 2018
Document and Entity Information    
Entity Registrant Name MADRIGAL PHARMACEUTICALS, INC.  
Entity Central Index Key 0001157601  
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Amendment Flag false  
Document Fiscal Period Focus Q3  
Document Fiscal Year Focus 2018  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Common Stock, Shares Outstanding   15,393,309