Cover - shares	9 Months Ended
	Sep. 30, 2022	Nov. 03, 2022
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	001-38947
Entity Registrant Name	BTRS HOLDINGS INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-3780685
Entity Address, Address Line One	1009 Lenox Drive
Entity Address, Address Line Two	Suite 101
Entity Address, City or Town	Lawrenceville
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08648
City Area Code	609
Local Phone Number	235-1010
Title of 12(b) Security	Class 1 Common Stock, $0.0001 par value
Trading Symbol	BTRS
Security Exchange Name	NASDAQ
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 Central Index Key	0001774155
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Class 1 Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		164,717,883
Common stock class 2
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		0