Acquisitions and Dispositions (Details) ft² in Thousands, $ in Thousands	1 Months Ended							3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) ft² tenant_space	Apr. 30, 2015 USD ($)	Oct. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	May. 31, 2014 USD ($)	Jan. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2011 USD ($)	Jun. 18, 2015 USD ($)	Apr. 30, 2014 USD ($)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Gross Sales Price												$ 26,060		$ 18,615
Net Proceeds												11,073		17,886
Gain												13,491		937
Loss on impairment								$ 2,781		$ 106		2,781	$ 17,256
Note receivable from sale of mall	$ 19,546							19,546				19,546		19,811
Gain on Extinguishment of Debt								256		0		256	$ 42,660
Eastgate Crossing
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Gross Sales Price	21,060
Net Proceeds	6,118
Gain	13,491
Earn out proceeds	$ 1,740
Minimum number of tenant spaces to be leased required to receive earn out proceeds | tenant_space	2
Minimum square feet per tenant space leased required to receive earn out proceeds | ft²	6
Mortgage loan assumed at sale	$ 14,570
Madison Square
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Gross Sales Price		$ 5,000
Net Proceeds		4,955
Gain		$ 0
Loss on impairment								2,620
Pemberton Plaza
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Gross Sales Price				$ 1,975
Net Proceeds				1,886
Gain				0
Loss on impairment									$ 497
Foothills Plaza Expansion [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Gross Sales Price					$ 2,640
Net Proceeds					2,387
Gain					$ 937
Lakeshore Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Gross Sales Price						$ 14,000
Net Proceeds						13,613
Gain						0
Loss on impairment										$ 106	$ 5,100
Columbia Place
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Loss on impairment																$ 50,683
Balance of Non-recourse Debt			$ 27,265
Gain on Extinguishment of Debt			$ 27,171
Noncash or Part Noncash Divestiture, Interest Expense														3,181
Chapel Hill Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Loss on impairment														12,050
Balance of Non-recourse Debt				68,563
Gain on Extinguishment of Debt				$ 18,296
Noncash or Part Noncash Divestiture, Interest Expense														1,514
Citadel Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Loss on impairment															$ 20,453
Balance of Non-recourse Debt							$ 68,169
Gain on Extinguishment of Debt							$ 43,932
Notes Receivable
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Note receivable from sale of mall	$ 10,488							$ 10,488				10,488		10,488
Notes Receivable | Lakeshore Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Note receivable from sale of mall						10,000
Cash | Lakeshore Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Net Proceeds						$ 4,000
Fair Value, Inputs, Level 3 | Lakeshore Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Fair value of real estate investments																		$ 13,780
Columbia Place Chapel Hill and Citadel Mall
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Balance of Non-recourse Debt														163,997
Gain on Extinguishment of Debt														$ 89,399
Mayfaire Town Center and Community Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business combination, ownership percentage																	100.00%
Revenue from acquiree included in consolidated financial statements												417
Income from acquiree included in consolidated financial statements												$ 187
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land																	$ 40,218
Buildings and improvements																	138,450
Tenant improvements																	3,382
Above-market leases																	279
In-place leases																	23,138
Total assets																	205,467
Below-market leases																	(13,479)
Net assets acquired																	$ 191,988