Earnings 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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income	$ 271,481	$ 321,299	$ 604,152	$ 430,556
Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties	$ (880)	$ (821)	$ (13,410)	$ (1,620)
Dilutive Securities Options	1,095	2,880	1,570	2,790
Denominator for net income per share – diluted	385,913	386,107	386,272	385,644
Net income per Unit – basic	$ 0.70	$ 0.83	$ 1.53	$ 1.11
Net income per Unit – diluted	$ 0.70	$ 0.83	$ 1.53	$ 1.11
ERPOP [Member]
Net income	$ 271,481	$ 321,299	$ 604,152	$ 430,556
Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties	(880)	(821)	(13,410)	(1,620)
Allocation to Preference Units	(772)	(772)	(1,545)	(1,545)
Numerator for net income per Unit – basic and diluted	$ 269,829	$ 319,706	$ 589,197	$ 427,391
Denominator for net income per Unit – basic	384,818	383,227	384,702	382,854
Dilutive Securities Options	1,095	2,880	1,570	2,790
Denominator for net income per share – diluted	385,913	386,107	386,272	385,644
Net income per Unit – basic	$ 0.70	$ 0.83	$ 1.53	$ 1.11
Net income per Unit – diluted	$ 0.70	$ 0.83	$ 1.53	$ 1.11