Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

PCAOB issued Audit Firm Identifier

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 10-K
-Number 249
-Section 310

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 20-F
-Number 249
-Section 220
-Subsection f

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 40-F
-Number 249
-Section 240
-Subsection f

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2021	Feb. 21, 2022	Jun. 30, 2021
Document Information [Line Items]
Entity Registrant Name	Broadmark Realty Capital Inc.
Entity Central Index Key	0001784797
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1.4
Entity Common Stock, Shares Outstanding		132,785,082
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement relating to its 2022 annual meeting of shareholders (the “2022 Proxy Statement”) are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. The 2022 Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K.
Auditor Name	Moss Adams LLP
Auditor Location	Everett, Washington
Auditor Firm ID	659
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