Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 02, 2022
Cover [Abstract]
Document Type	10-Q/A
Entity Registrant Name	BLACKROCK CAPITAL INVESTMENT CORPORATION
Document Quarterly Report	true
Entity Central Index Key	0001326003
Amendment Flag	true
Document Period End Date	Jun. 30, 2022
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Securities Act File Number	814-00712
Entity Tax Identification Number	20-2725151
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Trading Symbol	BKCC
Entity Common Stock, Shares Outstanding		73,196,436
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, Address Line One	40 East 52nd Street
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10022
City Area Code	212
Local Phone Number	810-5800
Amendment Description	EXPLANATORY NOTE The registrant’s Form 10-Q filed with the SEC on August 3, 2022 did not include inline XBRL tagging. The sole purpose of this Amendment No. 1 to the registrant’s Form 10-Q for the quarterly period ended June 30, 2022 is to add inline XBRL tagging to the Form 10-Q in accordance with Rule 405 of Regulation S-T.  No changes have been made to the registrant’s Form 10-Q. This Amendment No. 1 does not reflect any subsequent events occurring after the original filing date of the Form 10-Q or modify or update in any way disclosures made in the original filing.