Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 30, 2015
Document Information [Line Items]
Entity Registrant Name	STEWART INFORMATION SERVICES CORP
Entity Central Index Key	0000094344
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Trading Symbol	STC
Document Type	10-Q
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		22,235,588
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,050,012