v3.26.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2026
Apr. 30, 2026
Document Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Transition Report false  
Securities Act File Number 001-38258  
Entity Registrant Name MERCHANTS BANCORP  
Entity Incorporation, State or Country Code IN  
Entity Tax Identification Number 20-5747400  
Entity Address, Address Line One 410 Monon Blvd.  
Entity Address, City or Town Carmel  
Entity Address, State or Province IN  
Entity Address, Postal Zip Code 46032  
City Area Code 317  
Local Phone Number 569-7420  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   45,935,408
Entity Central Index Key 0001629019  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Common Class A    
Document Information    
Title of 12(b) Security Common Stock, without par value  
Trading Symbol MBIN  
Security Exchange Name NASDAQ  
Series C Preferred Stock    
Document Information    
Title of 12(b) Security Depositary Shares, each representing a 1/40th interest in a share of Series C Preferred Stock, without par value  
Trading Symbol MBINN  
Security Exchange Name NASDAQ  
Series D Preferred Stock    
Document Information    
Title of 12(b) Security Depositary Shares, each representing a 1/40th interest in a share of Series D Preferred Stock, without par value  
Trading Symbol MBINM  
Security Exchange Name NASDAQ  
Series E Preferred Stock    
Document Information    
Title of 12(b) Security Depositary Shares, each representing a 1/40th interest in a share of Series E Preferred Stock, without par value  
Trading Symbol MBINL  
Security Exchange Name NASDAQ