Net Income (Loss) Per Common Share Reconciling the Components of Basic and Diluted Net Income (Loss) per Common Share (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss) attributable to common shareholders/unitholders	$ 28,043	$ (36,390)
Less: Dividends on Participating Securities	(688)	(852)
Basic Net Income (Loss) Attributable To Common Stockholders	27,355	(37,242)
Net Income (Loss) Attributable to Noncontrolling Interest, Operating Partnerships	392	0
Diluted Net Income (Loss) Attributable to Common Stockholders	27,747	(37,242)
Weighted average number of common shares/units outstanding	314,936	258,365
Weighted Average Limited Partnership Units Outstanding	4,405	0
Other potential dilutive shares/units	230	0
Weighted average number of common shares/units and potential dilutive securities	319,571	258,365
Subsidiary of Common Parent [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss) attributable to common shareholders/unitholders	28,435	(37,201)
Less: Dividends on Participating Securities	(688)	(852)
Basic Net Income (Loss) Attributable To Common Stockholders	$ 27,747	$ (38,053)
Weighted average number of common shares/units outstanding	319,341	264,114
Other potential dilutive shares/units	230	0
Weighted average number of common shares/units and potential dilutive securities	319,571	264,114