Business Segments (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Capital additions	$ 75,898	$ 73,627
Same Store [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital additions	30,211	27,522
Redevelopment and Development [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital additions	39,048	43,481
Acquisition [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital additions	3,868	483
Other Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital additions	$ 2,771	$ 2,141