Earnings 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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 277,846	$ 223,846	$ 708,402	$ 562,804
Allocation to Noncontrolling Interests – Operating Partnership	(9,910)	(8,159)	(25,339)	(20,517)
Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Preferred distributions	(773)	(773)	(2,318)	(2,318)
Net income available to Common Shares	266,333	214,164	678,295	538,030
Numerator for net income per share – diluted	$ 276,243	$ 222,323	$ 703,634	$ 558,547
Weighted average Common Shares outstanding	370,768	368,028	370,227	367,920
OP Units	12,941	12,884	12,915	12,871
Dilutive Securities Options	3,187	2,972	3,035	2,642
Denominator for net income per share – diluted	386,896	383,884	386,177	383,433
Net income per share – basic	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Net income per share – diluted	$ 0.71	$ 0.58	$ 1.82	$ 1.46