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	113,955					112,374	1,581	113,955	16,905	95,469	1,234		347	113,608
Other comprehensive income	1,259				1,259			1,259				1,259		1,259
Issuance of common shares	601,927		431	601,496
Capital contribution from the General Partner								601,927		601,927				601,927
Stock based compensation plan activity	5,467		7	6,636		(1,176)		5,467		5,467				5,467
Conversion of Limited Partner Units			1	337			(338)			338	(338)
Distributions to preferred shareholders/unitholders	(16,905)					(16,905)		(16,905)	(16,905)					(16,905)
Redemption of preferred shares/units	(177,955)	(177,955)		5,932		(5,932)		(177,955)	(177,955)					(177,955)
Distributions to common shareholders	(109,554)					(109,554)
Distributions to Partners								(111,088)		(109,591)	(1,497)			(111,088)
Contributions from (distributions to) noncontrolling interests, net	(1,846)						(1,846)	(349)					(349)
Ending Balance - Partnership at Jun. 30, 2013								3,042,262	447,683	2,560,701	20,782	3,950	9,146	3,033,116
Ending Balance - General Partner at Jun. 30, 2013	3,042,466	447,683	3,233	4,567,898	3,950	(2,014,399)	34,101
Beginning Balance - Partnership at Mar. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	69,832							69,832
Other comprehensive income	722							722
Ending Balance - Partnership at Jun. 30, 2013								3,042,262
Ending Balance - General Partner at Jun. 30, 2013	$ 3,042,466