Debt (Details Textual)	1 Months Ended				3 Months Ended	12 Months Ended															12 Months Ended				1 Months Ended								12 Months Ended		12 Months Ended
	Jun. 30, 2011 USD ($)	Jun. 01, 2010 USD ($)	May 31, 2008 USD ($)	Nov. 30, 2007 USD ($)	Dec. 31, 2010 USD ($) Property	Dec. 31, 2011 USD ($) Y Loans Notes Property	Dec. 31, 2011 EUR (€)	Dec. 31, 2010 USD ($) Property	Dec. 31, 2009 USD ($)	Dec. 31, 2011 JPY (¥)	Nov. 24, 2011 USD ($)	Nov. 24, 2011 JPY (¥)	Jun. 03, 2011 USD ($)	Jun. 03, 2011 JPY (¥)	Oct. 31, 2009 USD ($)	Mar. 31, 2007 USD ($)	Dec. 31, 2011 Euro [Member] USD ($)	Dec. 31, 2011 Japanese yen [Member] USD ($)	Dec. 31, 2011 British sterling pound [Member] USD ($)	Dec. 31, 2011 Singapore Dollars [Member] USD ($)	Dec. 31, 2011 Properties fund eight [Member]	Mar. 15, 2010 3.25% convertible senior notes maturing in 2015 [Member]	Mar. 31, 2010 TMK bonds at 4.09% [Member]	Dec. 31, 2011 TMK bonds due March 2018 at 1.34% [Member] Bonds Property	Mar. 31, 2010 Convertible Note 2010 [Member] USD ($)	Mar. 31, 2007 Convertible Note in 2007 and 2008 [Member] USD ($)	Dec. 31, 2011 Convertible Debt [Member] Maximum [Member]	Dec. 31, 2011 Convertible Debt [Member] Minimum [Member]	Dec. 31, 2011 Other debt of consolidated investees [Member] Maximum [Member]	Dec. 31, 2011 Other debt of consolidated investees [Member] Minimum [Member]	Dec. 31, 2011 Consolidated Investees [Member] USD ($)	Jun. 30, 2011 Consolidated Investees [Member] USD ($)	Dec. 31, 2011 Secured mortgage debt [Member] USD ($)	Dec. 15, 2011 Secured mortgage debt [Member] USD ($) Property	Dec. 31, 2011 Secured mortgage debt [Member] Maximum [Member]	Dec. 31, 2011 Secured mortgage debt [Member] Minimum [Member]	Dec. 31, 2011 Secured mortgage debt [Member] April 2012 to May 2025 [Member] Maximum [Member]	Dec. 31, 2011 Secured mortgage debt [Member] April 2012 to May 2025 [Member] Minimum [Member]	Dec. 31, 2011 Other debt [Member] USD ($)	Dec. 15, 2011 Secured mortgage debt of consolidated investees [Member] USD ($)	Dec. 15, 2011 Secured mortgage debt of consolidated investees [Member] Secured mortgage debt due 2016 [Member] USD ($)	Dec. 15, 2011 Secured mortgage debt of consolidated investees [Member] Secured mortgage debt due december 2018 [Member] USD ($)	Dec. 31, 2011 Notes payable other payables [Member] Maximum [Member]	Dec. 31, 2011 Notes payable other payables [Member] Minimum [Member]
Senior And Other Notes Convertible Notes And Secured Mortgage Debt [Line Items]
Number of properties secured by debt						12	12																	3
Interest Rate																						3.25%	4.09%				5.86%	3.25%	5.88%	2.41%					7.58%	1.37%	7.58%	1.73%			4.58%	5.04%	9.34%	3.25%
Base principal amount per note																									$ 1,000	$ 1,000
Number of TMK bonds with merger																								2
Conversion price of exchangeable notes			$ 170.74	$ 182.24												$ 170.21									$ 38.72
Debt issued											38,700,000	3,000,000,000													460,000,000
Conversion rate of notes to shares of common stock			5.8564	5.4874																					25.8244	5.8752
Weighted average annual interest rate of secured mortgage debt					5.79%	5.12%	5.12%	5.79%																									0.00%
Payment of mortgage notes																																	68,000,000
Number of real estate properties					985	1,797	1,797	985																										28
Minimum interest rates						1.875%	1.875%																													0.00%
Maximum interest rates						8.70%	8.70%																												0.00%
Aggregate unpredictable cost of properties											147,000,000																							320,700,000					793,300,000
Secured mortgage debt incurred																																								177,000,000	103,000,000	74,000,000
Secured debt acquired in the merger																																	211,300,000
Percentage of partners interest acquired																					63.00%
Credit facility available borrowing line						60,000,000																									65,400,000	1,200,000,000
All Currencies [Line Items]
Foreign principal borrowing included in total debt						3,950,000,000											2,090,000,000	1,410,000,000	430,000,000	20,000,000
Debt (Textual) [Abstract]
Minimum percentage of ownership required in consolidated subsidiaries to provide guarantee to debt issued						100.00%	100.00%
Weighted average coupon interest rate					2.60%	2.60%	2.60%	2.60%
Senior notes aquired in the merger						1,710,000,000
Count of properties securing mortgage debt						219	219
Cost of properties securing mortgage debt						4,200,000,000
Count of properties securing consolidated investees mortgage debt						231	231
Cost of properties securing consolidated investees mortgage debt						3,200,000,000
Consolidated investee credit facility included in debt						54,600,000
Eurobond amount included in debt						559,100,000	427,600,000
Unsecured credit facilities included in debt						162,100,000	123,900,000
Repurchase of Eurobonds						118,600,000	86,000,000
Gain from Repurchase of Eurobonds						3,800,000
Assessment bonds included in other debt						18,600,000
Corporate term loans included in other debt						368,800,000
Global credit facility borrowing limit													1,750,000,000
Potential future global credit facility borrowing limit													2,750,000,000
Cross acceleration included in defaults						50,000,000
Debt revolver borrowing amount						471,300,000								36,500,000,000
Potential future debt revolver borrowing amount						729,600,000								56,500,000,000
Value of exchange offer	4,600,000,000
Amount of exchange offer validly tendered for exchange	4,400,000,000
Percentage of exchange offer validly tendered for exchange	95.00%
Fair value of derivative instruments						62,500,000
Fair Value of Derivative						18,000,000
Foreign currency exchange gain loss						44,500,000
Undepreciated value of properties securing bonds						271,400,000
Bonds acquired in merger						23,600,000
Mortgage notes acquired in merger						174,300,000				13,500,000,000
Undepreciated value of properties securing debt acquired in merger						48,500,000
Foreign term loan balance						161,300,000				12,500,000,000
Weighted average interest rate of foreign term loan						3.40%	3.40%
Senior unsecured term loan balance						201,000,000	154,000,000
Weighted average interest rate of senior unsecured term loan						3.40%	3.40%
Unsecured credit facilities included in maturities						215,200,000
Secured mortgage debt						145,800,000
Number of secured mortgage notes with merger						10	10
Share price beyond which shares required to include in the computation of diluted earnings per share			$ 140.82	$ 153.07												$ 142.97
Unamortized discount on debt					59,300,000	(60,000)		59,300,000
Additional paid in capital under conversion option						381,500,000		381,500,000
Maturity dates starts						2012	2012
Maturity dates ends						2033	2033
Amount of capitalized interest						88,000,000		381,800,000	290,200,000
Exchangeable Senior Notes Outstanding						6,100,000,000
Senior Notes Outstanding						6,100,000,000
Payment to record holder															2.50
principal amount of solicited notes															1,000
Solicited Notes Fees And Expenses															0
Reduced size of the aggregate commitments		2,250,000,000				1,600,000,000
Approximate represented premium						20% over the closing price of common stock	20% over the closing price of common stock
Percentage of closing price of common stock, represented premium						20.00%	20.00%
Aggregate borrowing capacity					1,601,500,000	2,184,600,000	487,500,000	1,601,500,000	2,164,800,000
Number of outstanding term loans						2	2
Increased borrowing limit						987,500,000
Principal payment period of consolidated debt						10	10
Consolidated Debt	12.1
Proceeds received from the contribution or sale of properties	1,000,000,000				1,020,000,000	1,100,000,000
Amount available in capital contribution						157,000,000
Company's share in capital contribution						$ 92,700,000