Consolidated Statement of Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Shares pursuant to dividend reinvestment plan (in shares)	61,861	96,268
Shares due to exercise of employee stock options and issuance of directors' deferred stock (in shares)	8,007	910
Limited Partner
Issuance of partnership units pursuant to dividend reinvestment plan (in shares)	13,704	19,493
Twinbrook Metro Station \| Restricted Stock Units (RSUs)
Restricted units released pursuant to first escrow release, shares		1,416,071
Dividend Distributions Payable
Distributions payable common stock, per share (in usd per share)	$ 0.57	$ 0.53
Distributions partnership units, per unit (in usd per share)	0.57	0.53
Series D Cumulative Redeemable Preferred Stock \| Dividend Distributions Payable
Distributions payable on preferred stock, per share (in usd per share)	38.28	38.28
Series E Cumulative Redeemable Preferred Stock \| Dividend Distributions Payable
Distributions payable on preferred stock, per share (in usd per share)	$ 37.50	$ 37.50

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