Equity (Details) $ / shares in Units, shares in Thousands, $ in Thousands				3 Months Ended		6 Months Ended
	Jul. 28, 2016 $ / shares	Apr. 27, 2016 $ / shares	Jan. 28, 2016 $ / shares	Jun. 30, 2016 USD ($) item $ / shares	Jun. 30, 2015 $ / shares	Jun. 30, 2016 USD ($) item $ / shares shares	Jun. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)
Equity
Dividends declared per common share (in dollars per share) | $ / shares	$ 0.575	$ 0.575	$ 0.575	$ 0.575	$ 0.565	$ 1.15	$ 1.13
Company's common stock issuances
Repurchase of common stock						$ 3,874	$ 7,690
Accumulated Other Comprehensive Loss
Cumulative foreign currency translation adjustment				$ (20,577)		(20,577)		$ (19,485)
Unrealized losses on cash flow hedges, net				(6,894)		(6,894)		(7,582)
Supplemental Executive Retirement Plan minimum liability				(3,270)		(3,270)		(3,411)
Unrealized gains on available for sale securities				3		3		8
Total accumulated other comprehensive loss				(30,738)		(30,738)		(30,470)
Noncontrolling interests
DownREIT unit, carrying value				$ 180,587		$ 180,587		$ 185,608
Common Stock
Company's common stock issuances
Dividend Reinvestment and Stock Purchase Plan (in shares) | shares						1,427	1,645
Conversion of DownREIT units (in shares) | shares						120	70
Exercise of stock options (in shares) | shares						111	817
Vesting of restricted stock units (in shares) | shares						288	379
Repurchase of common stock						$ 109	$ 171
Noncontrolling Interests
Noncontrolling interests
Non-managing members DownREIT units outstanding | item				4,000,000		4,000,000
Number of DownREIT LLCs | item				5		5
DownREIT unit, carrying value				$ 181,000		$ 181,000
DownREIT unit, fair value				$ 207,000		$ 207,000