Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 08, 2021
Document Information Line Items
Entity Registrant Name	AEROCENTURY CORP
Trading Symbol	ACY
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		4,416,811
Amendment Flag	false
Entity Central Index Key	0001036848
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-13387
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3263974
Entity Address, Address Line One	3000 El Camino Real
Entity Address, Address Line Two	Bldg. 4, Suite 200
Entity Address, City or Town	Palo Alto
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94306
City Area Code	(650)
Local Phone Number	340-1888
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NYSE
Entity Interactive Data Current	Yes