Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Operating real estate, consolidated variable interest entities	$ 2,210,901	$ 2,207,648
Construction-in-progress, consolidated variable interest entities	21,677	18,752
Accumulated depreciation and amortization, consolidated variable interest entities	403,533	389,950
Mortgages payable, consolidated variable interest entities	$ 334,640	$ 335,301
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, authorized	15,000,000	15,000,000
Common shares of beneficial interest, par value	$ 0.01	$ 0.01
Common shares of beneficial interest, shares outstanding	79,417,472	78,603,305
Common shares of beneficial interest, shares issued	79,417,472	78,603,305
Common shares of beneficial interest, shares authorized	100,000,000	100,000,000
Federal Realty OP LP
Operating real estate, consolidated variable interest entities	$ 2,210,901	$ 2,207,648
Construction-in-progress, consolidated variable interest entities	21,677	18,752
Accumulated depreciation and amortization, consolidated variable interest entities	403,533	389,950
Mortgages payable, consolidated variable interest entities	$ 334,640	$ 335,301
Preferred units, issued	405,896	405,896
Preferred units, outstanding	405,896	405,896
Common units, issued	79,417,472	78,603,305
Common units, outstanding	79,417,472	78,603,305
5.0% Series C Cumulative Redeemable Preferred Shares, (stated at liquidation preference $25,000 per share), 6,000 shares issued and outstanding
Preferred shares, percentage	5.00%	5.00%
Preferred shares, liquidation preference	$ 25,000	$ 25,000
Preferred shares, shares outstanding	6,000	6,000
Preferred shares, shares issued	6,000	6,000
5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 399,896 shares issued and outstanding
Preferred shares, percentage	5.417%	5.417%
Preferred shares, liquidation preference	$ 25	$ 25
Preferred shares, shares outstanding	399,896	399,896
Preferred shares, shares issued	399,896	399,896