Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Line Items]
Income (loss) from continuing operations attributable to common shareholders									$ 152,808	$ (44,703)	$ (37,008)
Income (loss) from discontinued operations attributable to common shareholders									4,041	(59,018)	(21,088)
Net income (loss) attributable to common shareholders									156,849	(103,721)	(58,096)
Weighted-average common shares outstanding – basic									159,109,424	152,473,336	130,985,809
Income (loss) from continuing operations									$ 0.96	$ (0.29)	$ (0.28)
Income (loss) from discontinued operations									$ 0.03	$ (0.39)	$ (0.16)
Net income (loss) attributable to common shareholders	$ (0.04)	$ 1.09	$ (0.02)	$ (0.01)					$ 0.99	$ (0.68)	$ (0.44)
Impact of assumed conversions:
Share Options									0	0	0
Operating Partnership Units									1,371	0	0
6.00% Convertible Guaranteed Notes									8,953	0	0
Income (loss) from continuing operations attributable to common shareholders									163,132	(44,703)	(37,008)
Income (loss) from discontinued operations attributable to common shareholders									4,041	(59,018)	(21,088)
Operating Partnership Units									(179)	0	0
Income (loss) from discontinued operations attributable to common shareholders									3,862	(59,018)	(21,088)
Net income (loss) attributable to common shareholders									166,994	(103,721)	(58,096)
Effect of dilutive securities:
Share Options									306,449	0	0
Operating Partnership Units									4,438,708	0	0
6.00% Convertible Guaranteed Notes									15,805,245	0	0
Weighted-average common shares outstanding									179,659,826	152,473,336	130,985,809
Income (loss) per common share:
Income (loss) from continuing operations (USD per share)									$ 0.91	$ (0.29)	$ (0.28)
Income (loss) from discontinued operations (USD per share)									$ 0.02	$ (0.39)	$ (0.16)
Net income (loss) attributable to common shareholders (USD per share)	$ (0.04)	$ 0.96	$ (0.02)	$ (0.01)	$ 0.05	$ (0.24)	$ (0.33)	$ (0.16)	$ 0.93	$ (0.68)	$ (0.44)
Earnings Per Share
Common shares issued	178,616,664				154,938,351				178,616,664	154,938,351
Series C | Cumulative Convertible
Earnings Per Share
Preferred shares repurchased and retired									34,800,000	125,000,000
Discount to historical cost basis	229				833				229	833
Series B | Cumulative Redeemable
Earnings Per Share
Preferred shares repurchased and retired									2,740,874,000	419,126,000
Premium to historical cost	$ 2,346				$ 95				$ 2,346	$ 95