Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	[1]	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Computation of basic and diluted earnings per share
Numerator for basic and diluted earnings per share - net income attributable to common stockholders	$ 333,044	$ 334,910		$ 195,474	$ 148,969	$ 132,929	$ 182,043	$ 312,573	$ 190,799	$ 1,012,397	$ 818,344	$ 446,745
Basic										358,275,000	348,240,000	306,272,000
Effect of dilutive securities:
Employee stock options										110,000	143,000	188,000
Non-vested restricted shares										449,000	535,000	500,000
Redeemable shares										1,393,000	310,000	0
Convertible senior unsecured notes										0	196,000	787,000
Dilutive potential common shares										1,952,000	1,184,000	1,475,000
Diluted										360,227,000	349,424,000	307,747,000
Basic earnings per share	$ 0.92	$ 0.93		$ 0.55	$ 0.42	$ 0.38	$ 0.52	$ 0.89	$ 0.57	$ 2.83	$ 2.35	$ 1.46
Diluted earnings per share	$ 0.91	$ 0.93		$ 0.54	$ 0.42	$ 0.37	$ 0.52	$ 0.89	$ 0.56	$ 2.81	$ 2.34	$ 1.45
Earnings Per Share (Textuals) [Abstract]
Securities Excluded From Computation Of Diluted Earnings Per Share										0	0	0

[1] The increase in net income and amounts per share are primarily attributable to gains on sales of real estate of $162,351,000 for the third quarter as compared to gains of $1,530,000 for the second quarter.