Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Summary information for the reportable segments
Total revenues	$ 224,200	$ 250,187	$ 454,435	$ 497,907
Other operating expenses not allocated to segments	108,257	124,795	217,894	240,851
Total operating expenses	184,096	200,826	372,917	395,169
Proportionate property net operating income	40,104	49,361	81,518	102,738
Other items included in income before income tax benefit (expense)	28,065	(46,512)	280,927	(38,716)
Income before income tax benefit (expense)	68,169	2,849	362,445	64,022
Real Estate [Member]
Summary information for the reportable segments
Total revenues	224,200	231,130	454,435	456,523
Property operating expenses	75,839	76,031	155,023	154,318
Segment Reconciling Items [Member]
Summary information for the reportable segments
Total revenues	8,255	7,640	16,884	15,767
Total operating expenses	7,725	7,116	15,792	14,734
Proportionate property net operating income	530	524	1,092	1,033
Income before income tax benefit (expense)	530	524	1,092	1,033
Segment Reconciling Items [Member] | Real Estate [Member]
Summary information for the reportable segments
Property operating expenses	7,725	7,116	15,792	14,734
Corporate Non-Segment [Member]
Summary information for the reportable segments
Total revenues	892	38,427	8,570	82,023
Other operating expenses not allocated to segments	108,257	124,795	217,894	240,851
Total operating expenses	115,294	134,868	235,287	264,417
Proportionate property net operating income	(114,402)	(96,441)	(226,717)	(182,394)
Other items included in income before income tax benefit (expense)	28,065	(46,512)	280,927	(38,716)
Income before income tax benefit (expense)	(86,337)	(142,953)	54,210	(221,110)
Corporate Non-Segment [Member] | Real Estate [Member]
Summary information for the reportable segments
Property operating expenses	7,037	10,073	17,393	23,566
Same Store [Member] | Operating Segments [Member]
Summary information for the reportable segments
Total revenues	176,375	169,902	350,494	336,931
Total operating expenses	47,169	46,352	93,904	92,659
Proportionate property net operating income	129,206	123,550	256,590	244,272
Income before income tax benefit (expense)	129,206	123,550	256,590	244,272
Same Store [Member] | Operating Segments [Member] | Real Estate [Member]
Summary information for the reportable segments
Property operating expenses	47,169	46,352	93,904	92,659
Redevelopment and Development [Member] | Operating Segments [Member]
Summary information for the reportable segments
Total revenues	19,166	18,482	39,516	36,560
Total operating expenses	7,030	6,936	14,317	13,436
Proportionate property net operating income	12,136	11,546	25,199	23,124
Income before income tax benefit (expense)	12,136	11,546	25,199	23,124
Redevelopment and Development [Member] | Operating Segments [Member] | Real Estate [Member]
Summary information for the reportable segments
Property operating expenses	7,030	6,936	14,317	13,436
Acquisition [Member] | Operating Segments [Member]
Summary information for the reportable segments
Total revenues	10,237	6,358	20,230	7,937
Total operating expenses	2,974	1,875	5,827	2,398
Proportionate property net operating income	7,263	4,483	14,403	5,539
Income before income tax benefit (expense)	7,263	4,483	14,403	5,539
Acquisition [Member] | Operating Segments [Member] | Real Estate [Member]
Summary information for the reportable segments
Property operating expenses	2,974	1,875	5,827	2,398
Other Real Estate [Member] | Operating Segments [Member]
Summary information for the reportable segments
Total revenues	9,275	9,378	18,741	18,689
Total operating expenses	3,904	3,679	7,790	7,525
Proportionate property net operating income	5,371	5,699	10,951	11,164
Income before income tax benefit (expense)	5,371	5,699	10,951	11,164
Other Real Estate [Member] | Operating Segments [Member] | Real Estate [Member]
Summary information for the reportable segments
Property operating expenses	$ 3,904	$ 3,679	$ 7,790	$ 7,525