Segment Reporting (Summary of Net Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement [Line Items]
Straight-line rental income and expense, net	$ 1,703	$ 5,704
Equity in earnings of unconsolidated joint ventures	2,539	4,715
Interest expense	(23,494)	(22,132)
Depreciation and amortization expense	(85,359)	(75,992)
Gain on sale of properties	8,937	(163)
Impairment charges	(5,626)	0
Interest and other income, net	1,395	2,758
General and administrative expenses	(21,763)	(21,983)
Gain on land sales	135	750
Other operating expenses	(1,112)	(2,123)
Loss on extinguishment of debt	(17,806)	(13)
Gain on involuntary conversion	0	2,259
Non-incremental costs related to successful leases	2,525	2,156
Income from continuing operations before income taxes	19,552	45,153
Operating Segments [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	158,880	143,370
Property Level Net Income, Cash Basis, Continuing Operations	158,994	149,362
Operating Segments [Member] | Industrial [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	157,061	142,494
Operating Segments [Member] | All Other Segments [Member]
Statement [Line Items]
Property Level Net Operating Income – Cash Basis	1,819	876
Operating Segments [Member] | Service Operations [Member]
Statement [Line Items]
Earnings from Service Operations	1,046	2,378
Segment Reconciling Items [Member]
Statement [Line Items]
PNOI from sold properties included in continuing operations	114	5,992
Straight-line rental income and expense, net	1,703	5,704
Revenues Related to Lease Buyouts	392	19
Amortization of lease concessions and above and below market rents	2,557	1,262
Intercompany rents and other adjusting items	(394)	433
Corporate, Non-Segment [Member]
Statement [Line Items]
Equity in earnings of unconsolidated joint ventures	2,539	4,715
Interest expense	(23,494)	(22,132)
Depreciation and amortization expense	(85,359)	(75,992)
Gain on sale of properties	8,937	(163)
Interest and other income, net	1,395	2,758
General and administrative expenses	(21,763)	(21,983)
Gain on land sales	135	750
Other operating expenses	(1,112)	(2,123)
Loss on extinguishment of debt	(17,806)	(13)
Gain on involuntary conversion	0	(2,259)
Non-incremental costs related to successful leases	(2,525)	(2,156)
Other non-segment revenues and expenses, net	$ (67)	$ 75