Consolidated Statement of Changes in Stockholders' Equity and Noncontrolling Interests (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Series D Cumulative Convertible Preferred Stock	Series E Cumulative Redeemable Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests	Redeemable Noncontrolling Interests
Balance as of December 31, 2012 at Dec. 31, 2012	$ 3,488,494	$ 250,000	$ 130,000	$ 632	$ 3,086,052	$ 0	$ (24,833)	$ 46,643	$ 14,564
Balance (in shares) at Dec. 31, 2012				63,244,645
Increase (Decrease) in Stockholders' Equity
Net income	63,037					61,612		1,425	537
Unrealized gain on marketable securities	130						130
Unrealized gain on interest rate swap agreements	8,114						8,114
Foreign currency translation loss	(23,057)						(22,976)	(81)
Distributions to noncontrolling interests	(639)							(639)	(596)
Issuance of common stock (in shares)				7,590,000
Issuance of common stock	534,850			76	534,774
Issuances pursuant to stock plan (in shares)				162,745
Issuances pursuant to stock plan	11,663			2	11,661
Dividends declared on common stock	(84,680)					(84,680)
Dividends declared on preferred stock	(12,942)					(12,942)
Distributions in excess of earnings					(36,010)	36,010
Balance as of June 30, 2013 at Jun. 30, 2013	$ 3,984,970	$ 250,000	$ 130,000	$ 710	$ 3,596,477	$ 0	$ (39,565)	$ 47,348	$ 14,505
Balance (in shares) at Jun. 30, 2013				70,997,390