Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Current Fiscal Year End Date			--12-31
Transfer from investment in unconsolidated joint ventures to projects under development			$ 5,880	$ 0
Transfer from operating properties to operating properties and related assets held for sale			0	86,775
Transfer from operating properties to liabilities of real estate assets held for sale				0	$ 3,132
Net income	$ (7,765)	$ (7,951)	(30,561)	(15,155)
Adjustments to reconcile net loss to net cash provided by operating activities:
Gain on sale of investment properties, including discontinued operations			13,944	(21)
Depreciation and amortization, including discontinued operations			64,350	70,381
Amortization of deferred financing costs			699	716
Net amortization of stock options and restricted stock			1,153	808
Effect of certain non-cash adjustments to rental revenues			(9,656)	(15,047)
Income Loss from Unconsolidated Joint Ventures			3,618	3,372
Operating distributions from unconsolidated joint ventures			4,209	1,820
Changes in other operating assets and liabilities:
Change in other receivables and other assets, net			(5,188)	(10,106)
Change in operating liabilities			(8,472)	(15,311)
Net cash provided by operating activities			60,094	45,065
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from investment property sales			21,088	9,164
Property acquisition, development, and tenant asset expenditures			(75,594)	(73,344)
Investment in unconsolidated joint ventures			(22,281)	(3,443)
Distributions from unconsolidated joint ventures			4,099	1,649
Change in notes receivable and other assets			0	772
Change in restricted cash			(876)	(652)
Net cash used in investing activities			(73,564)	(65,854)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from credit facility			163,700	114,100
Repayment of credit facility			(100,700)	(52,300)
Repayment of notes payable			(4,589)	(4,371)
Proceeds from the Issuance of Common Stock, including Option Exercises			0	9
Proceeds from (Payments to) Noncontrolling Interests			1,473	0
Preferred Stock Redemption			(13,743)	0
Common dividends paid			(33,728)	(34,677)
Net cash provided by financing activities			12,413	22,761
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS			(1,057)	1,972
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD			2,003	0
CASH AND CASH EQUIVALENTS AT END OF PERIOD	946	1,972	946	1,972
Interest paid, net of amounts capitalized			14,131	15,477
Accrued property acquisition, development, and tenant asset expenditures	$ 3,891	$ 416	$ 3,891	$ 416