Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 11, 2022	Jun. 30, 2021
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Entity File Number	000-16335
Entity Registrant Name	RIDGEFIELD ACQUISITION CORP
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	84-0922701
Entity Address, Address Line One	3250 Retail Drive
Entity Address, Address Line Two	Suite 120 - 518
Entity Address, City or Town	Carson City
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89706-0686
City Area Code	805
Local Phone Number	484-8855
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	true
Entity Common Stock, Shares Outstanding		2,860,773
Entity Central Index Key	0000812152
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Trading Symbol	RDGA
Title of 12(g) Security	Common Stock, $0.001 par value
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 779,158
ICFR Auditor Attestation Flag	false
Auditor Name	MaloneBailey, LLP
Auditor Firm ID	206
Auditor Location	Houston, Texas