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
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 109,257	$ 220,548
Allocation to Noncontrolling Interests – Operating Partnership	(3,919)	(8,059)
Partially Owned Properties	(799)	(680)
Preferred distributions	(773)	(773)
Net income available to Common Shares	103,766	211,036
Numerator for net income per share – diluted	$ 107,685	$ 219,095
Weighted average Common Shares outstanding	369,558	367,800
OP Units	12,919	12,863
Dilutive Securities Options	2,707	2,355
Denominator for net income per share – diluted	385,184	383,018
Net income available to Common Shares	$ 0.28	$ 0.57
Net income available to Common Shares	$ 0.28	$ 0.57