FAIR VALUE MEASUREMENTS - Long-Lived Assets Measure at Fair Value (Details) $ in Thousands	1 Months Ended			3 Months Ended								12 Months Ended
	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) property	Sep. 30, 2016 USD ($) mall	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) property	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) property mall outparcel office_building anchor_store	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) property outparcel	Dec. 31, 2014 USD ($) property	Apr. 30, 2015 USD ($)	Apr. 30, 2014 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment												$ 116,822				$ 105,945	$ 17,858
Fair Value				$ 46,200			$ 125,000					46,200				125,000
Purchase Price								$ 191,988
Mortgage and other indebtedness, net				$ 4,465,294			$ 4,710,628					$ 4,465,294				$ 4,710,628
Number of properties disposed of | property																	3
Number of properties written down | property				113			4					113				4
Air Transportation Equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment																	$ 105
Net proceeds from sale of real estate																	176
Real estate investment property, net																	$ 281
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value				$ 46,200			$ 125,000					$ 46,200				$ 125,000
The Lakes and Fashion Square, Wausau Center, Bonita Lakes, Midland Mall and Ridge River Mall
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment												$ 116,822
Number of Malls with Impairment | mall												9
Number of Office Buildings with Impairment | office_building												3
Number of Stores with Impairment | outparcel												3
Randolph Mall, Regency Mall, and Walnut Square
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment	$ 43,144			(150)	$ 43,294
Number of Malls with Impairment | mall					3
Fair Value	31,318			0	$ 31,318							$ 0	$ 31,318
Purchase Price	32,250				32,250								$ 32,250
Concentration risk, percent of total revenue													1.50%
One and Two Oyster Point
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment	3,844
Number of Office Buildings with Impairment | office_building												2
Fair Value				6,000								$ 6,000
Concentration risk, percent of total revenue												0.30%
Capitalization rate (as a percent)												8.00%
Discount rate (as a percent)												10.00%
Estimated selling costs as percentage of total fair value												2.00%
Oak Branch Business Center
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment	100			(22)	122
Fair Value				0								$ 0
Cobblestone Village at Palm Coast
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment	$ 6,448			150	$ 6,298
Fair Value				0								0
Concentration risk, percent of total revenue													0.10%
Capitalization rate (as a percent)					9.00%
Discount rate (as a percent)					10.75%
Estimated selling costs as percentage of total fair value					2.00%
The Lakes and Fashion Square
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment		$ 32,096
Fair Value		65,447		0								0		$ 65,447
Purchase Price		66,500												$ 66,500
Concentration risk, percent of total revenue														1.60%
Wausau Center
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment		$ 10,738
Fair Value				11,000								$ 11,000
Concentration risk, percent of total revenue												0.30%
Holding period (in years)												10 years
Capitalization rate (as a percent)												13.25%
Discount rate (as a percent)												13.00%
Estimated selling costs as percentage of total fair value												4.00%
Number of stores sold | anchor_store												2
Bonita Lakes Mall and Crossing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment			$ 5,323
Fair Value			27,440	0		$ 27,440						$ 0			$ 27,440
Purchase Price			27,910			27,910									$ 27,910
Concentration risk, percent of total revenue															0.70%
Midland Mall
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment			4,681
Fair Value				29,200								$ 29,200
Concentration risk, percent of total revenue												0.60%
Holding period (in years)												10 years
Capitalization rate (as a percent)												9.75%
Discount rate (as a percent)												11.50%
Estimated selling costs as percentage of total fair value												2.00%
River Ridge Mall
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment			$ 9,594	84		9,510
Fair Value				0								$ 0
Concentration risk, percent of total revenue															0.60%
Outparcel Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment																$ 884
Non-cash impairment of long-lived asset												$ 854
Number of properties disposed of												3				2
Chesterfield Mall
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment							99,969
Fair Value							125,000									$ 125,000
Concentration risk, percent of total revenue																1.50%
Holding period (in years)																11 years
Capitalization rate (as a percent)																8.25%
Discount rate (as a percent)																8.25%
Chapel Hill Crossing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment							1,914
Net proceeds from sale of real estate							2,300
Mayfaire Community Center
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment							397
Net proceeds from sale of real estate							56,300
Madison Square
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment								$ 2,620
Fair Value																		$ 5,000
Burlington
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment																$ 161
Net proceeds from sale of real estate																750
Carrying amount							$ 911									$ 911
Chapel Hill Suburban
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment											$ 12,050
Concentration risk, percent of total revenue																	0.40%
Chapel Hill Suburban | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value											53,348
Lakeshore Mall
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment										$ 106	$ 5,100
Concentration risk, percent of total revenue																	0.20%
Lakeshore Mall | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value																			$ 13,780
Pemberton Plaza
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment									$ 497
Concentration risk, percent of total revenue																	0.00%
Minimum | One and Two Oyster Point
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Holding period (in years)												1 year
Maximum | One and Two Oyster Point
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Holding period (in years)												2 years
Non Recourse Loans On Operating Properties | Wausau Center
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage and other indebtedness, net				17,689								$ 17,689
River Ridge Mall
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment				$ 84		9,510						$ 9,594
Percentage owned in disposed asset			75.00%									75.00%
Reserve for future capital expenditures						$ 2,100						$ 2,100
Retail Site
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment												$ 115,968