Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 09, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Registrant Name	RIDGEFIELD ACQUISITION CORP
Entity Central Index Key	0000812152
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Trading Symbol	RDGA
Entity Common Stock, Shares Outstanding		1,260,773
Entity Emerging Growth Company	false
Entity Small Business	true