Segment Reporting (Summary of Net Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement [Line Items]
Straight-line rental income and expense, net			$ 15,660	$ 15,627
Equity in earnings of unconsolidated joint ventures	$ 4,023	$ 3,736	8,958	12,594
Interest expense	(23,059)	(22,604)	(69,394)	(68,246)
Depreciation and amortization expense	(88,596)	(83,924)	(260,659)	(242,920)
Gain on sale of properties	10,968	173,646	19,905	204,075
Impairment charges	0	0	(5,626)	0
Interest and other income, net	32	2,085	1,643	7,377
General and administrative expenses	(11,439)	(13,720)	(46,808)	(49,123)
Gain on land sales	2,346	3,869	8,551	6,569
Other operating expenses	(1,772)	(874)	(4,430)	(4,515)
Loss on extinguishment of debt	(120)	0	(32,898)	(13)
Gain on involuntary conversion	3,029	0	4,312	2,259
Non-incremental costs related to successful leases	4,058	1,123	10,617	6,726
Income from continuing operations before income taxes	71,520	227,883	131,119	351,221
Operating Segments [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	169,215	151,555	488,937	445,098
Property Level Net Income, Cash Basis, Continuing Operations	169,320	155,908	489,608	461,843
Operating Segments [Member] | Industrial [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	168,123	150,672	484,973	442,475
Operating Segments [Member] | All Other Segments [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	1,092	883	3,964	2,623
Operating Segments [Member] | Service Operations [Member]
Statement [Line Items]
Earnings from Service Operations	2,033	2,315	4,810	5,423
Segment Reconciling Items [Member]
Statement [Line Items]
PNOI from sold properties included in continuing operations	105	4,353	671	16,745
Straight-line rental income and expense, net	7,184	5,161	15,660	15,627
Revenues Related to Lease Buyouts	179	1,465	2,605	1,484
Amortization of lease concessions and above and below market rents	1,746	1,741	5,843	4,545
Intercompany rents and other adjusting items	(624)	77	(999)	180
Corporate, Non-Segment [Member]
Statement [Line Items]
Equity in earnings of unconsolidated joint ventures	4,023	3,736	8,958	12,594
Interest expense	(23,059)	(22,604)	(69,394)	(68,246)
Depreciation and amortization expense	(88,596)	(83,924)	(260,659)	(242,920)
Gain on sale of properties	10,968	173,646	19,905	204,075
Interest and other income, net	32	2,085	1,643	7,377
General and administrative expenses	(11,439)	(13,720)	(46,808)	(49,123)
Gain on land sales	2,346	3,869	8,551	6,569
Other operating expenses	(1,772)	(874)	(4,430)	(4,515)
Loss on extinguishment of debt	(120)	0	(32,898)	(13)
Gain on involuntary conversion	3,029	0	4,312	2,259
Non-incremental costs related to successful leases	(4,058)	(1,123)	(10,617)	(6,726)
Other non-segment revenues and expenses, net	$ 328	$ 125	$ 655	$ 788