Document And Entity Information	3 Months Ended
	Mar. 31, 2021 shares
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Registrant Name	BCTC V ASSIGNOR CORP
Title of 12(b) Security	None
No Trading Symbol Flag	true
Entity Central Index Key	0001267426
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Shell Company	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	1,000