Earnings Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Computation of basic and diluted earnings per share
Numerator for basic and diluted earnings per share - net income (loss) attributable to common stockholders	$ 71,829,000	$ (8,508,000)	$ 121,851,000	$ 46,551,000
Denominator for basic earnings per share - weighted average shares	296,256,000	273,091,000	293,046,000	266,602,000
Effect of dilutive securities:
Employee stock options	191,000	283,000	170,000	0
Non-vested restricted shares	472,000	370,000	506,000	0
Convertible senior unsecured notes	1,076,000	2,737,000	868,000	0
Dilutive potential common shares	1,739,000	3,390,000	1,544,000	0
Denominator for diluted earnings per share - adjusted weighted average shares	297,995,000	276,481,000	294,590,000	266,602,000
Basic earnings per share	$ 0.24	$ (0.03)	$ 0.42	$ 0.17
Diluted earnings per share	$ 0.24	$ (0.03)	$ 0.41	$ 0.17
Earnings Per Share (Textual) [Abstract]
Securities Excluded From Computation Of Diluted Earnings Per Share	0	0	0	0