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		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 95,365	$ 277,846	$ 699,517	$ 708,402
Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties	$ (703)	$ (830)	$ (14,113)	$ (2,450)
Dilutive Securities Options	781	3,187	1,214	3,035
Denominator for net income per share – diluted	385,652	386,896	385,973	386,177
Net income per Unit – basic	$ 0.24	$ 0.72	$ 1.77	$ 1.83
Net income per Unit – diluted	$ 0.24	$ 0.71	$ 1.77	$ 1.82
ERPOP [Member]
Net income	$ 95,365	$ 277,846	$ 699,517	$ 708,402
Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties	(703)	(830)	(14,113)	(2,450)
Allocation to Preference Units	(773)	(773)	(2,318)	(2,318)
Numerator for net income per Unit – basic and diluted	$ 93,889	$ 276,243	$ 683,086	$ 703,634
Denominator for net income per Unit – basic	384,871	383,709	384,759	383,142
Dilutive Securities Options	781	3,187	1,214	3,035
Denominator for net income per share – diluted	385,652	386,896	385,973	386,177
Net income per Unit – basic	$ 0.24	$ 0.72	$ 1.77	$ 1.83
Net income per Unit – diluted	$ 0.24	$ 0.71	$ 1.77	$ 1.82