Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 01, 2022
Document Information [Line Items]
Entity Registrant Name	Broadmark Realty Capital Inc.
Entity Central Index Key	0001784797
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2022
Entity File Number	001-39134
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	84-2620891
Entity Address, Address Line One	1420 Fifth Avenue, Suite 2000
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98101
City Area Code	206
Local Phone Number	971-0800
Current Fiscal Year End Date	--12-31
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		132,866,617
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Amendment Flag	false
Common Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock
Trading Symbol	BRMK
Security Exchange Name	NYSE
Warrant
Document Information [Line Items]
Title of 12(b) Security	Warrants
Trading Symbol	BRMK WS
Security Exchange Name	NYSEAMER