Schedule III - Real Estate and Accumulated Depreciation (Changes in Total Real Estate Assets and Accumulated Depreciation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule III - Real Estate and Accumulated Depreciation [Abstract]
Balance, beginning of period	$ 7,667,743	$ 7,376,690	$ 7,387,597
Acquisition of operating properties and unconsolidated joint ventures	286,901	56,985	0
Development and repositions	300,294	224,202	278,447
Improvements	84,841	71,889	65,892
Cost of real estate sold – other	(11,304)	(62,023)	(355,246)
Balance, end of period	8,328,475	7,667,743	7,376,690
Balance, Beginning of period	2,118,839	1,890,656	1,780,694
Depreciation of real estate assets	284,310	255,924	243,403
Dispositions	0	(27,741)	(133,441)
Balance, End of period	2,403,149	$ 2,118,839	$ 1,890,656
Real Estate, Federal Income Tax Basis	$ 7,500,000