Earnings Per Share And Unit (Schedule Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net income	$ 59,392	$ 158,774	$ 180,127	$ 277,969
Less: Preferred share dividends	(2,008)	(2,008)	(6,024)	(6,026)
Less: Income from operations attributable to noncontrolling interests	(2,344)	(2,636)	(7,245)	(8,171)
Less: Earnings allocated to unvested shares	(323)	(535)	(974)	(935)
Net income available for common shareholders, basic	54,717	153,595	165,884	262,837
Add: Income attributable to downREIT operating partnership units	0	704	0	2,111
Net income available for common shareholders, diluted	$ 54,717	$ 154,432	$ 165,884	$ 264,948
Weighted average common shares outstanding, basic	81,274	80,765	81,210	79,480
Open forward contracts for share issuances	0	0	0	1
DownREIT operating partnership units	0	652	0	656
Weighted average common shares outstanding, diluted	81,274	81,511	81,210	80,137
EARNINGS PER COMMON SHARE, BASIC:
Net income available for common shareholders	$ 0.67	$ 1.90	$ 2.04	$ 3.31
EARNINGS PER COMMON SHARE, DILUTED:
Net income available for common shareholders	$ 0.67	$ 1.89	$ 2.04	$ 3.31
5.417% Series 1 Cumulative Convertible Preferred Shares
Add: Dividends on 5.417% Series 1 Cumulative Convertible Preferred Shares	$ 0	$ 133	$ 0	$ 0
5.417% Series 1 Cumulative Convertible Preferred Shares	0	94	0	0
Federal Realty OP LP
Net income	$ 59,392	$ 158,774	$ 180,127	$ 277,969
Less: Preferred unit distributions	(2,008)	(2,008)	(6,024)	(6,026)
Less: Income from operations attributable to noncontrolling interests	(2,344)	(2,636)	(7,245)	(8,171)
Less: Earnings allocated to unvested units	(323)	(535)	(974)	(935)
Net income available for common unit holders, basic	54,717	153,595	165,884	262,837
Add: Income attributable to downREIT operating partnership units	0	704	0	2,111
Net income available for common unit holders, diluted	$ 54,717	$ 154,432	$ 165,884	$ 264,948
Weighted average common units outstanding, basic	81,274	80,765	81,210	79,480
Common unit issuances relating to open common share forward contracts	0	0	0	1
DownREIT operating partnership units	0	652	0	656
Weighted average common units outstanding, diluted	81,274	81,511	81,210	80,137
EARNINGS PER COMMON UNIT, BASIC:
Net income available for common unit holders	$ 0.67	$ 1.90	$ 2.04	$ 3.31
EARNINGS PER COMMON UNIT, DILUTED:
Net income available for common unit holders	$ 0.67	$ 1.89	$ 2.04	$ 3.31
Federal Realty OP LP | Preferred Units
Add: Dividends on 5.417% Series 1 Cumulative Convertible Preferred Units	$ 0	$ 133	$ 0	$ 0
5.417% Series 1 Cumulative Convertible Preferred Units	0	94	0	0