Segment Reporting (Summary of Net Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement [Line Items]
Straight-line rental income and expense, net			$ 15,627	$ 16,763
Equity in earnings of unconsolidated joint ventures	$ 3,736	$ 5,552	12,594	15,521
Interest expense	(22,604)	(21,462)	(68,246)	(62,137)
Depreciation and amortization expense	(83,924)	(78,855)	(242,920)	(232,216)
Gain on sale of properties	173,646	(107)	204,075	194,741
Interest and other income, net	2,085	4,129	7,377	13,319
General and administrative expenses	(13,720)	(8,959)	(49,123)	(43,441)
Gain on land sales	3,869	3,915	6,569	7,221
Other operating expenses	(874)	(1,104)	(4,515)	(3,902)
Loss on extinguishment of debt	0	(89)	(13)	(240)
Gain on involuntary conversion	0	0	2,259	0
Non-incremental costs related to successful leases	1,123	0	6,726	0
Income from continuing operations before income taxes	227,883	52,405	351,221	329,072
Operating Segments [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	152,789	137,768	449,069	395,674
Property Level Net Income, Cash Basis, Continuing Operations	155,908	143,314	461,843	420,342
Operating Segments [Member] | Industrial [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	151,906	136,456	446,446	391,645
Operating Segments [Member] | All Other Segments [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	883	1,312	2,623	4,029
Operating Segments [Member] | Service Operations [Member]
Statement [Line Items]
Earnings from Service Operations	2,315	1,256	5,423	5,160
Segment Reconciling Items [Member]
Statement [Line Items]
PNOI from sold properties included in continuing operations	3,119	5,546	12,774	24,668
Straight-line rental income and expense, net	5,537	5,832	16,003	16,763
Revenues Related to Lease Buyouts	1,089	0	1,108	23
Amortization of lease concessions and above and below market rents	1,741	593	4,545	1,599
Intercompany rents and other adjusting items	77	48	180	206
Corporate, Non-Segment [Member]
Statement [Line Items]
Equity in earnings of unconsolidated joint ventures	3,736	5,552	12,594	15,521
Interest expense	(22,604)	(21,462)	(68,246)	(62,137)
Depreciation and amortization expense	(83,924)	(78,855)	(242,920)	(232,216)
Gain on sale of properties	173,646	(107)	204,075	194,741
Interest and other income, net	2,085	4,129	7,377	13,319
General and administrative expenses	(13,720)	(8,959)	(49,123)	(43,441)
Gain on land sales	3,869	3,915	6,569	7,221
Other operating expenses	(874)	(1,104)	(4,515)	(3,902)
Loss on extinguishment of debt	0	(89)	(13)	(240)
Gain on involuntary conversion	0	0	2,259	0
Non-incremental costs related to successful leases	(1,123)	0	(6,726)	0
Other non-segment revenues and expenses, net	$ 125	$ (1,658)	$ 788	$ (3,887)