Segment Reporting Summary of Net Operating Income (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Straight-line rental income and expense, net	$ 16,051,000	$ 13,743,000	$ 22,396,000
Equity in earnings (loss) of unconsolidated joint ventures	63,310,000	47,403,000	(3,304,000)
Gain on dissolution of unconsolidated joint venture	0	30,697,000	0
Promote income	20,007,000	26,299,000	0
Interest Expense	(87,003,000)	(112,757,000)	(138,258,000)
Depreciation and amortization expense	(273,561,000)	(242,557,000)	(245,764,000)
Gain on sale of properties	113,669,000	162,093,000	229,702,000
Impairment Charges	(4,481,000)	(18,018,000)	(22,932,000)
Interest and other income, net	14,721,000	4,035,000	4,667,000
General and Administrative Expense	(54,944,000)	(55,389,000)	(58,565,000)
Gain on land sales	9,244,000	9,865,000	35,054,000
Other operating expenses	(2,554,000)	(3,864,000)	(5,947,000)
Loss on debt extinguishment	(26,104,000)	(33,934,000)	(85,713,000)
Acquisition-related activity	0	7,176,000	(8,499,000)
Income from continuing operations before income taxes	290,235,000	297,832,000	184,320,000
Operating Segments [Member]
Segment Reporting Information [Line Items]
Property Level Net Operating Income – Cash Basis	487,056,000	429,858,000	389,495,000
PNOI, continuing operations	493,593,000	467,537,000	466,645,000
Operating Segments [Member] | Industrial [Member]
Segment Reporting Information [Line Items]
Property Level Net Operating Income – Cash Basis	482,025,000	423,924,000	380,213,000
Operating Segments [Member] | Non-Reportable Rental Operations
Segment Reporting Information [Line Items]
Property Level Net Operating Income – Cash Basis	5,031,000	5,934,000	9,282,000
Operating Segments [Member] | Earnings from Service Operations
Segment Reporting Information [Line Items]
Earnings from Service Operations	4,963,000	8,343,000	14,197,000
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
PNOI from sold/held-for-sale properties included in continuing operations	6,537,000	37,679,000	77,150,000
Straight-line rental income and expense, net	13,585,000	7,897,000	14,595,000
Revenues related to lease buyouts	10,816,000	1,725,000	1,567,000
Amortization of lease concessions and above and below market rents	(1,732,000)	(2,126,000)	(6,113,000)
Intercompany rents and other adjusting items	(304,000)	(2,640,000)	(3,947,000)
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Equity in earnings (loss) of unconsolidated joint ventures	63,310,000	47,403,000	(3,304,000)
Gain on dissolution of unconsolidated joint venture	0	30,697,000	0
Promote income	20,007,000	26,299,000	0
Interest Expense	(87,003,000)	(112,757,000)	(138,258,000)
Depreciation and amortization expense	(273,561,000)	(242,557,000)	(245,764,000)
Gain on sale of properties	113,669,000	162,093,000	229,702,000
Impairment Charges	(4,481,000)	(18,018,000)	(22,932,000)
Interest and other income, net	14,721,000	4,035,000	4,667,000
General and Administrative Expense	(54,944,000)	(55,389,000)	(58,565,000)
Gain on land sales	9,244,000	9,865,000	35,054,000
Other operating expenses	(2,554,000)	(3,864,000)	(5,947,000)
Loss on debt extinguishment	(26,104,000)	(33,934,000)	(85,713,000)
Acquisition-related activity	0	7,176,000	(8,499,000)
Other non-segment revenues and expenses, net	$ (2,990,000)	$ (3,953,000)	$ (3,065,000)