Equity (Details) $ / shares in Units, shares in Thousands, $ in Thousands			1 Months Ended		3 Months Ended								12 Months Ended
	Jan. 28, 2016 $ / shares	Oct. 07, 2015 USD ($) property	Oct. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) item $ / shares	Sep. 30, 2015 $ / shares	Jun. 30, 2015 $ / shares	Mar. 31, 2015 $ / shares	Dec. 31, 2014 USD ($) $ / shares	Sep. 30, 2014 $ / shares	Jun. 30, 2014 $ / shares	Mar. 31, 2014 $ / shares	Dec. 31, 2015 USD ($) item $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares
Equity
Dividends declared per common share (in dollars per share) | $ / shares	$ 0.575												$ 2.26	$ 2.18	$ 2.10
Dividends paid per common share (in dollars per share) | $ / shares					$ 0.565	$ 0.565	$ 0.565	$ 0.565	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 2.26	$ 2.18	$ 2.10
Maximum sales under equity offering program				$ 750,000
Common stock issued (in shares) | shares													1,800
Weighted average price (in dollars per share) | $ / shares					$ 40.14								$ 40.14
Proceeds from issuance of common stock													$ 73,000
Stock issuance fees and commissions													1,000
Company's common stock issuances
Repurchase of common stock													8,738	$ 12,703	$ 10,438
Accumulated Other Comprehensive Loss
Cumulative foreign currency translation adjustment					$ (19,485)				$ (10,747)				(19,485)	(10,747)
Unrealized losses on cash flow hedges, net					(7,582)				(9,624)				(7,582)	(9,624)
Supplemental Executive Retirement Plan minimum liability					(3,411)				(3,537)				(3,411)	(3,537)
Unrealized gains on available for sale securities					8				13				8	13
Total accumulated other comprehensive loss					(30,470)				(23,895)				$ (30,470)	(23,895)
Noncontrolling interests
Number of Down REIT units | item													4,000,000
DownREIT unit, carrying value					$ 185,608				$ 188,588				$ 185,608	$ 188,588
HCP Ventures V
Noncontrolling interests
Number of Real Estate Properties | property		11
HCP Ventures V
Noncontrolling interests
Noncontrolling interest (as a percent)		49.00%	49.00%
Consideration received from sale of noncontrolling interest in HCP Ventures V		$ 110,000	$ 110,000
Common Stock
Equity
Common stock issued (in shares) | shares													5,117	2,939	3,136
Company's common stock issuances
Dividend Reinvestment and Stock Purchase Plan (in shares) | shares													2,762	2,299	2,441
Conversion of DownREIT units (in shares) | shares													104	27	100
Exercise of stock options (in shares) | shares													823	169	876
Vesting of restricted stock units (in shares) | shares													409	614	471
Repurchase of common stock													$ 198	$ 323	$ 242
Noncontrolling Interests
Company's common stock issuances
Conversion of DownREIT units (in shares) | shares													6,000
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					$ 186,000								$ 186,000
DownREIT unit, fair value					$ 229,000								$ 229,000