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	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net income (loss) attributable to common shareholders	$ (32,076)	$ 34,064	$ (13,549)	$ (23,591)
Less: Dividends on participating securities	(811)	(694)	(2,416)	(1,699)
Basic net income (loss) attributable to common shareholders	(32,887)	33,370	(15,965)	(25,290)
Noncontrolling interest in earnings of common unitholders	0	1,041	0	0
Diluted net income (loss) attributable to common shareholders	$ (32,887)	$ 34,411	$ (15,965)	$ (25,290)
Weighted average number of common shares outstanding	252,802	251,866	252,618	234,468
Weighted average partnership Units outstanding	0	5,517	0	0
Other potential dilutive shares	0	0	0	0
Weighted average number of common shares and potential dilutive securities	252,802	257,383	252,618	234,468
3.75% Exchangeable Senior Notes [Member]
Interest rate stated on the debt instrument	3.75%		3.75%

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