Earnings Per Share (Details) (USD $)	3 Months Ended										12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Computation of basic and diluted earnings per share
Numerator for basic and diluted earnings per share - net income attributable to common stockholders	$ 11,473,000	$ 20,691,000	$ (8,508,000)	[1]	$ 55,058,000	$ 90,576,000	$ 37,269,000	[2]	$ 54,735,000	$ 39,307,000	$ 78,714,000	$ 221,884,000	$ 157,108,000
Basic											276,929,000	224,343,000	173,741,000
Effect of dilutive securities:
Employee stock options											226,000	231,000	176,000
Non-vested restricted shares											457,000	312,000	246,000
Convertible senior unsecured notes											1,149,000	1,067,000	238,000
Dilutive potential common shares											1,832,000	1,610,000	660,000
Diluted											278,761,000	225,953,000	174,401,000
Basic earnings per share	$ 0.04	$ 0.07	$ (0.03)	[1]	$ 0.21	$ 0.35	$ 0.17	[2]	$ 0.26	$ 0.2	$ 0.28	$ 0.99	$ 0.9
Diluted earnings per share	$ 0.04	$ 0.07	$ (0.03)	[1]	$ 0.21	$ 0.35	$ 0.16	[2]	$ 0.25	$ 0.19	$ 0.28	$ 0.98	$ 0.9
Earnings Per Share (Textuals) [Abstract]
Securities Excluded From Computation Of Diluted Earnings Per Share											0	182,000	0

[1] The decrease in net income and amounts per share are primarily attributable to gains on sales of real estate of $82,492,000 for the first quarter as compared to losses of $29,997,000 for the second quarter.

[2] The decrease in net income and amounts per share are primarily attributable to gains on sales of real estate of $32,450,000 for the second quarter as compared to $12,827,000 for the third quarter.