Consolidated Statement of Changes in Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Distributions in Excess of Net Income [Member]	Non-controlling Interest [Member]	Subsidiary of Common Parent [Member]	Subsidiary of Common Parent [Member] Preferred Stock [Member]	Subsidiary of Common Parent [Member] Common Stock [Member]	Subsidiary of Common Parent [Member] Limited Partner [Member]	Subsidiary of Common Parent [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Subsidiary of Common Parent [Member] Non-controlling Interest [Member]	Subsidiary of Common Parent [Member] Stockholders' Equity, Total [Member]
Beginning Balance - Partnership at Dec. 31, 2012								$ 2,625,951	$ 625,638	$ 1,967,091	$ 21,383	$ 2,691	$ 9,148	$ 2,616,803
Beginning Balance - General Partner at Dec. 31, 2012	2,626,118	625,638	2,794	3,953,497	2,691	(1,993,206)	34,704
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	115,292					113,663	1,629	115,292	24,261	89,402	1,142		487	114,805
Other comprehensive income	1,089				1,089			1,089				1,089		1,089
Issuance of common shares	632,531		451	632,080
Capital contribution from the General Partner								632,531		632,531				632,531
Stock based compensation plan activity	7,633		7	9,378		(1,752)		7,633		7,633				7,633
Conversion of Limited Partner Units			1	337			(338)			338	(338)
Distributions to preferred shareholders/unitholders	(24,261)					(24,261)		(24,261)	(24,261)					(24,261)
Redemption of preferred shares/units	(177,955)	(177,955)		5,932		(5,932)		(177,955)	(177,955)					(177,955)
Distributions to common shareholders	(164,811)					(164,811)
Distributions to Partners								(167,092)		(164,849)	(2,243)			(167,092)
Contributions from (distributions to) noncontrolling interests, net	(2,692)						(2,692)	(449)					(449)
Ending Balance - Partnership at Sep. 30, 2013								3,012,739	447,683	2,532,146	19,944	3,780	9,186	3,003,553
Ending Balance - General Partner at Sep. 30, 2013	3,012,944	447,683	3,253	4,601,224	3,780	(2,076,299)	33,303
Beginning Balance - Partnership at Jun. 30, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,337							1,337
Other comprehensive income	(170)							(170)
Ending Balance - Partnership at Sep. 30, 2013								3,012,739
Ending Balance - General Partner at Sep. 30, 2013	$ 3,012,944