Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document Documentand Entity Information [Abstract]
Entity Registrant Name	SAFEGUARD SCIENTIFICS INC
Entity Central Index Key	0000086115
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Common Stock, Shares Outstanding		20,576,575
Trading Symbol	SFE