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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss) attributable to common shareholders/unitholders	$ 61,494	$ (28,482)	$ 89,537	$ (64,872)
Less: Dividends on Participating Securities	(688)	(856)	(1,375)	(1,708)
Basic Net Income (Loss) Attributable To Common Stockholders	60,806	(29,338)	88,162	(66,580)
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable	842	0	1,234	0
Diluted Net Income (Loss) Attributable to Common Stockholders	61,648	(29,338)	89,396	(66,580)
Weighted average number of common shares/units outstanding	322,489	266,748	318,733	262,556
Weighted Average Limited Partnership Units Outstanding	4,388	0	4,397	0
Other potential dilutive shares/units	221	0	220	0
Weighted average number of common shares/units and potential dilutive securities	327,098	266,748	323,350	262,556
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	62,336	(28,948)	90,771	(66,149)
Less: Dividends on Participating Securities	(688)	(856)	(1,375)	(1,708)
Basic Net Income (Loss) Attributable To Common Stockholders	$ 61,648	$ (29,804)	$ 89,396	$ (67,857)
Weighted average number of common shares/units outstanding	326,877	271,317	323,130	267,716
Other potential dilutive shares/units	221	0	220	0
Weighted average number of common shares/units and potential dilutive securities	327,098	271,317	323,350	267,716