Class of Stock [Domain] Class of Stock [Domain] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entities [Table] Entities [Table] Class of Stock [Axis] Class of Stock [Axis] Federal Realty OP LP Federal Realty OP LP [Member] Federal Realty OP LP Security Exchange Name Security Exchange Name Depository Shares Depository Shares [Member] Depository Shares [Member] Entity Address, City or Town Entity Address, City or Town Soliciting Material Soliciting Material Cover [Abstract] Cover [Abstract] Legal Entity [Axis] Legal Entity [Axis] City Area Code City Area Code Amendment Flag Amendment Flag Entity Tax Identification Number Entity Tax Identification Number Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Pre-commencement Tender Offer Pre-commencement Tender Offer Entity Emerging Growth Company Entity Emerging Growth Company Common Shares Of Beneficial Interest Common Shares Of Beneficial Interest [Member] Common Shares Of Beneficial Interest [Member] Entity Central Index Key Entity Central Index Key Entity File Number Entity File Number Entity Address, State or Province Entity Address, State or Province Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Entity Address, Address Line One Entity Address, Address Line One Entity Address, Postal Zip Code Entity Address, Postal Zip Code Written Communications Written Communications Local Phone Number Local Phone Number Entity [Domain] Entity [Domain] Title of 12(b) Security Title of 12(b) Security Document Period End Date Document Period End Date Entity Information [Line Items] Entity Information [Line Items] Document Type Document Type