Document and Entity Information Document	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2013	Apr. 26, 2013
Entity Information [Line Items]
Entity Registrant Name	FEDERAL REALTY INVESTMENT TRUST
Entity Central Index Key	0000034903
Current Fiscal Year End Date		--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2013
Document Fiscal Year Focus		2013
Document Fiscal Period Focus	Q1
Amendment Flag	false
Trading Symbol	FRT
Entity Common Stock, Shares Outstanding			65,243,839
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes