Earning Per Share and Earnings Per Unit - Computation of Net Income per Unit Basic and Net Income per Unit Diluted for Operating Partnership (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income (loss) from continuing operations	$ 144,196	$ 217,246	$ 498,297	$ 4,177,599
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(801)	(823)	(2,354)	(2,368)
Discontinued operations, net	$ 0	$ 246	$ 0	$ 124
Weighted average Common Shares outstanding	382,945	382,373	382,640	382,284
Net income available to Common Shares	$ 0.37	$ 0.57	$ 1.30	$ 11.00
Net income available to Common Shares	0.37	0.56	1.29	10.92
Income from continuing operations available to Common Shares	0.37	0.57	1.30	11.00
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0	0	0
Earnings Per Share, Basic	0.37	0.57	1.30	11.00
Income from continuing operations available to Common Shares	0.37	0.56	1.29	10.92
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0	0	0
Earnings Per Share, Diluted	$ 0.37	$ 0.56	$ 1.29	$ 10.92
ERPOP [Member]
Income (loss) from continuing operations	$ 144,196	$ 217,246	$ 498,297	$ 4,177,599
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(801)	(823)	(2,354)	(2,368)
Allocation to Preference Units	(772)	(773)	(2,318)	(2,318)
Income Loss From Continuing Operations Available To Units	142,623	215,650	493,625	4,172,913
Discontinued operations, net	0	246	0	124
Numerator for net income per Unit – basic and diluted	$ 142,623	$ 215,896	$ 493,625	$ 4,173,037
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	379,906	379,008	379,716	378,745
Dilutive Securities Options	3,039	3,365	2,924	3,539
Weighted average Common Shares outstanding	382,945	382,373	382,640	382,284
Net income available to Common Shares	$ 0.37	$ 0.57	$ 1.30	$ 11.00
Net income available to Common Shares	0.37	0.56	1.29	10.92
Income from continuing operations available to Common Shares	0.37	0.57	1.30	11.00
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0	0	0
Earnings Per Share, Basic	0.37	0.57	1.30	11.00
Income from continuing operations available to Common Shares	0.37	0.56	1.29	10.92
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0	0	0
Earnings Per Share, Diluted	$ 0.37	$ 0.56	$ 1.29	$ 10.92