Earning Per Share and Earnings Per Unit - Computation of Net Income per Share Basic and Net Income per Share Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ 204,160	$ 228,365	$ 354,101	$ 3,960,353
Allocation to Noncontrolling Interests – Operating Partnership, net	(7,354)	(8,779)	(12,765)	(152,093)
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(765)	(781)	(1,553)	(1,545)
Preferred distributions	(773)	(772)	(1,546)	(1,545)
Income from continuing operations available to Common Shares, net of Noncontrolling Interests	195,268	218,033	338,237	3,805,170
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	34	0	(118)
Net income available to Common Shares	195,268	218,067	338,237	3,805,052
Income From Continuing Operations Available To Common Shares	202,622	226,812	351,002	3,957,263
Discontinued operations, net	0	35	0	(122)
Net Income (Loss) Available to Common Stockholders, Diluted	$ 202,622	$ 226,847	$ 351,002	$ 3,957,141
Weighted average Common Shares outstanding	366,820	365,047	366,713	364,820
Dilutive Op Units	12,913	13,887	12,906	13,792
Long-term compensation shares/units	2,959	3,131	2,886	3,400
Weighted average Common Shares outstanding	382,692	382,065	382,505	382,012
Net income available to Common Shares	$ 0.53	$ 0.60	$ 0.92	$ 10.43
Net income available to Common Shares	0.53	0.59	0.92	10.36
Income from continuing operations available to Common Shares	0.53	0.60	0.92	10.43
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0	0	0
Income from continuing operations available to Common Shares	0.53	0.59	0.92	10.36
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	$ 0	$ 0	$ 0	$ 0