Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Computation of basic and diluted earnings per share
Numerator for basic and diluted earnings per share - net income (loss) attributable to common stockholders	$ 55,058		$ 39,307
Denominator for basic earnings per share - weighted average shares	260,036,000		199,661,000
Effect of dilutive securities:
Employee stock options	0		223,000
Non-vested restricted shares	0		280,000
Convertible senior unsecured notes	0		1,494,000
Dilutive potential common shares	0		1,997,000
Denominator for diluted earnings per share - adjusted weighted average shares	260,036,000		201,658,000
Basic earnings per share	$ 0.21	[1]	$ 0.20	[1]
Diluted earnings per share	$ 0.21	[1]	$ 0.19	[1]
Earnings Per Share (Textual) [Abstract]
Securities Excluded From Computation Of Diluted Earnings Per Share	0		388,000

[1] Amounts may not sum due to rounding