Business Segments (Details 1) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 6,240,804	$ 6,190,004
Corporate Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	323,275	432,095
Same Store [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	4,110,917	4,131,494
Redevelopment and Development [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	852,177	792,126
Acquisition [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	627,109	507,190
Other Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	$ 327,326	$ 327,099