Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares issued pursuant to dividend reinvestment plan	293,615,000	228,498,000	430,462,000
Shares due to exercise of employee stock options and issuance of directors' deferred stock	70,231,000	16,887,000	61,571,000
Issuance of partnership units (in shares)		51,579,000	60,936,000
Limited Partner
Shares issued pursuant to dividend reinvestment plan	61,009,000
Twinbrook Metro Station
Stock issued during period, shares, acquisitions	469,740,000
Twinbrook Metro Station | Restricted Stock Units (RSUs)
Stock issued during period, shares, acquisitions	1,416,071,000
Restricted Units Released Pursuant to First Escrow Release, Shares	708,036,000
Ashbrook Marketplace
Stock issued during period, shares, acquisitions	93,674,000
Series C Cumulative Preferred Stock
Redemption of Series C Cumulative preferred stock (in shares)			42,000,000
Series E Cumulative Redeemable Preferred Stock
Issuance of Series D Cumulative preferred stock (in shares)			44,000,000
Dividend declared
Distributions payable common stock and partnership units (in usd per share)	$ 0.57	$ 0.53	$ 0.53
Dividend declared | Series D Cumulative Redeemable Preferred Stock
Distributions payable on preferred stock (in usd per share)	38.28	38.28	38.28
Dividend declared | Series E Cumulative Redeemable Preferred Stock
Distributions payable on preferred stock (in usd per share)	$ 37.50	$ 37.50	$ 37.50