Condensed Consolidated Statements of Changes in Equity (Unaudited) (USD $) In Thousands, except Share data	Total	Accumulated Distributions in Excess of Net Income [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Parent [Member]	Noncontrolling Interest [Member]	Comprehensive Income [Member]
Balance at Dec. 31, 2009	$ 5,117,978	$ (338,738)	$ (96,432)	$ 884	$ 4,055	$ 5,283,204	$ 4,852,973	$ 265,005
Balance (in Shares) at Dec. 31, 2009				884,000	405,533,000
Contributions from noncontrolling interests	2,380							2,380
Comprehensive income:
Net iincome	81,987	75,447					75,447	6,540	81,987
Other comprehensive income, net of tax:
Unrealized gain (loss) on marketable securities	1,841		1,841				1,841		1,841
Change in unrealized gain (loss) on interest rate swaps	(507)		(507)				(507)		(507)
Change in foreign currency translation adjustment	46,797		30,079				30,079	16,718	46,797
Comprehensive income	130,118								130,118
Redeemable noncontrolling interests	(3,244)							(3,244)
Dividends	(153,486)	(153,486)					(153,486)
Distributions to noncontrolling interests	(55,460)							(55,460)
Issuance of common stock	5,269				4	5,265	5,269
Issuance of common stock (in Shares)					353,000
Surrender of common stock	(644)				(1)	(643)	(644)
Surrender of common stock (in Shares)					(66,000)
Exercise of common stock options	171					171	171
Exercise of common stock options (in Shares)					13,000
Acquisition of noncontrolling interests	(11,790)					(8,028)	(8,028)	(3,762)
Amortization of equity awards	6,522					6,522	6,522
Balance at Jun. 30, 2010	5,037,814	(416,777)	(65,019)	884	4,058	5,286,491	4,809,637	228,177
Balance (in Shares) at Jun. 30, 2010				884,000	405,833,000
Balance at Dec. 31, 2010	5,161,286	(515,164)	(23,853)	954	4,064	5,469,841	4,935,842	225,444
Balance (in Shares) at Dec. 31, 2010				954,000	406,424,000
Contributions from noncontrolling interests	952							952
Comprehensive income:
Net iincome	73,336	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)		(2,129)
Change in unrealized gain (loss) on interest rate swaps	259		259				259		259
Change in foreign currency translation adjustment	58,032		53,712				53,712	4,320	58,032
Comprehensive income	129,498								129,498
Redeemable noncontrolling interests	(3,161)							(3,161)
Dividends	(176,636)	(176,636)					(176,636)
Distributions to noncontrolling interests	(4,272)							(4,272)
Issuance of common stock	4,940				5	4,935	4,940
Issuance of common stock (in Shares)					438,000
Surrender of common stock	(244)					(244)	(244)
Surrender of common stock (in Shares)					(13,000)
Repurchase of common stock	(1,415)				(1)	(1,414)	(1,415)
Repurchase of common stock (in Shares)					(74,000)
Exercise of common stock options	2,828				2	2,826	2,828
Exercise of common stock options (in Shares)					184,000
Acquisition of noncontrolling interests	(9,702)					887	887	(10,589)
Amortization of equity awards	7,571					7,571	7,571
Balance at Jun. 30, 2011	$ 5,111,645	$ (624,129)	$ 27,989	$ 954	$ 4,070	$ 5,484,402	$ 4,893,286	$ 218,359
Balance (in Shares) at Jun. 30, 2011				954,000	406,959,000