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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 321,299	$ 118,410	$ 430,556	$ 338,958
Allocation to Noncontrolling Interests – Operating Partnership	(11,510)	(4,299)	(15,429)	(12,358)
Partially Owned Properties	(821)	(509)	(1,620)	(1,189)
Preferred distributions	(772)	(772)	(1,545)	(1,545)
Net income available to Common Shares	308,196	112,830	411,962	323,866
Numerator for net income per share – diluted	$ 319,706	$ 117,129	$ 427,391	$ 336,224
Weighted average Common Shares outstanding	370,342	367,930	369,952	367,865
OP Units	12,885	12,865	12,902	12,864
Dilutive Securities Options	2,880	2,628	2,790	2,495
Denominator for net income per share – diluted	386,107	383,423	385,644	383,224
Net income per share – basic	$ 0.83	$ 0.31	$ 1.11	$ 0.88
Net income per share – diluted	$ 0.83	$ 0.31	$ 1.11	$ 0.88