Summary Of Significant Accounting Policies (Variable Interest Entities) (Details) $ in Thousands	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Variable Interest Entity [Line Items]
Number of consolidated variable interest entities	18
Net real estate assets of consolidated VIEs	$ 1,500,000	$ 1,400,000
Mortgage Payable From Consolidated Variable Interest Entities	444,388	460,372
Unconsolidated variable interest entities
Variable Interest Entity [Line Items]
Maximum exposure to loss in variable interest entity	$ 26,900	$ 23,900

Mortgages payable balances from variable interest entities, or VIEs, for the periods presented.

No definition available.

Name:	frt_MortgagePayableFromConsolidatedVariableInterestEntities
Namespace Prefix:	frt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of consolidated entities that meet the criteria of a variable interest entity in which the Company holds a variable interest under ASU 2015-02.

+ References

No definition available.

+ Details

Name:	frt_NumberofConsolidatedVariableInterestEntities
Namespace Prefix:	frt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The net carrying amount of the consolidated Variable Interest Entity's assets and liabilities included in the reporting entity's statement of financial position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5710-111685

+ Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssetsAndLiabilitiesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5747-111685

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5728-111685

+ Details

Name:	us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_UnconsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: