Condensed Consolidated Statements of Changes in Equity (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Accumulated Distributions in Excess of Net Income [Member] USD ($)	Accumulated Other Comprehensive Income (Loss) [Member] Interest Rate Swap [Member] USD ($)	Accumulated Other Comprehensive Income (Loss) [Member] USD ($)	Preferred Stock [Member] USD ($)	Preferred Stock [Member] USD ($)	Common Stock [Member] USD ($)	Common Stock [Member] USD ($)	Additional Paid-in Capital [Member] Common Stock [Member] USD ($)	Additional Paid-in Capital [Member] Preferred Stock [Member] USD ($)	Additional Paid-in Capital [Member] USD ($)	Parent [Member] Interest Rate Swap [Member] USD ($)	Parent [Member] Common Stock [Member] USD ($)	Parent [Member] Preferred Stock [Member] USD ($)	Parent [Member] USD ($)	Noncontrolling Interest [Member] USD ($)	Interest Rate Swap [Member] USD ($)	Common Stock [Member] USD ($)	Series I Preferred Stock [Member]	Preferred Stock [Member] USD ($)	Total USD ($)
Balance at Dec. 31, 2010	$ (515,164)		$ (23,853)		$ 954		$ 4,064			$ 5,469,841				$ 4,935,842	$ 225,444					$ 5,161,286
Balance (in Shares) at Dec. 31, 2010					954,000		406,424,000
Contributions from noncontrolling interests															952					952
Comprehensive income:
Net income	67,671													67,671	5,665					73,336
Other comprehensive income, net of tax:
Unrealized gain (loss) on marketable securities			(2,129)											(2,129)						(2,129)
Change in unrealized gain on interest rate swaps		259									259					259
Change in foreign currency translation adjustment			53,712											53,712	4,320					58,032
Redeemable noncontrolling interests															(3,161)					(3,161)
Dividends	(176,636)													(176,636)						(176,636)
Distributions to noncontrolling interests															(4,272)					(4,272)
Issuance of stock						5		4,935				4,940					4,940
Issuance of stock (in Shares)						438,000
Surrender of common stock										(244)				(244)						(244)
Surrender of common stock (in Shares)							(13,000)
Repurchase of common stock							(1)			(1,414)				(1,415)						(1,415)
Repurchase of common stock (in Shares)							(74,000)
Exercise of common stock options							2			2,826				2,828						2,828
Exercise of common stock options (in Shares)							184,000
Acquisition of noncontrolling interests										887				887	(10,589)					(9,702)
Amortization of equity awards										7,571				7,571						7,571
Balance at Jun. 30, 2011	(624,129)		27,989		954		4,070			5,484,402				4,893,286	218,359					5,111,645
Balance (in Shares) at Jun. 30, 2011					954,000		406,959,000
Balance at Mar. 31, 2011
Comprehensive income:
Net income																				41,315
Other comprehensive income, net of tax:
Unrealized gain (loss) on marketable securities																				1,914
Change in unrealized gain on interest rate swaps																128
Balance at Jun. 30, 2011					954															5,111,645
Balance (in Shares) at Jun. 30, 2011					954,000
Balance at Dec. 31, 2011					954
Balance (in Shares) at Dec. 31, 2011					954,000
Other comprehensive income, net of tax:
Issuance of stock (in Shares)																		16,000,000
Balance at Mar. 31, 2012
Balance at Dec. 31, 2011	(702,999)		(107,660)		954		4,069			5,492,022				4,686,386	193,757					4,880,143
Balance (in Shares) at Dec. 31, 2011					954,000		406,938,000
Contributions from noncontrolling interests															1,201					1,201
Comprehensive income:
Net income	122,750													122,750	8,785					131,535
Other comprehensive income, net of tax:
Unrealized gain (loss) on marketable securities			928											928						928
Change in unrealized gain on interest rate swaps		372									372					372
Change in foreign currency translation adjustment			6,471											6,471	3,101					9,572
Redeemable noncontrolling interests															(3,148)					(3,148)
Dividends	(191,033)													(191,033)						(191,033)
Distributions to noncontrolling interests															(8,823)					(8,823)
Issuance of stock				16		11		18,055	387,214			18,066	387,230				18,066		387,230
Issuance of stock (in Shares)				16,000		1,093,000
Surrender of common stock										(1,555)				(1,555)						(1,555)
Surrender of common stock (in Shares)							(84,000)
Repurchase of common stock							(16)			(28,942)				(28,958)						(28,958)
Repurchase of common stock (in Shares)							(1,536,000)													(1,500,000)
Exercise of common stock options							5			7,174				7,179						7,179
Exercise of common stock options (in Shares)							480,000
Acquisition of noncontrolling interests										(1,244)				(1,244)	(4,392)					(5,636)
Amortization of equity awards										8,016				8,016						8,016
Balance at Jun. 30, 2012	(771,282)		(99,889)		970		4,069			5,880,740				5,014,608	190,481					5,205,089
Balance (in Shares) at Jun. 30, 2012					970,000		406,891,000
Balance at Mar. 31, 2012
Comprehensive income:
Net income																				72,387
Other comprehensive income, net of tax:
Unrealized gain (loss) on marketable securities																				(231)
Change in unrealized gain on interest rate swaps																179
Balance at Jun. 30, 2012					$ 970															$ 5,205,089
Balance (in Shares) at Jun. 30, 2012					970,000