Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 01, 2020
Document and Entity Information
Entity Registrant Name	MERCHANTS BANCORP
Entity Central Index Key	0001629019
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		28,742,484
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1