INVESTMENTS IN AND ADVANCES TO UNCONSOLIDATED AFFILIATES (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Combined and Condensed Balance Sheets
Real estate under development	$ 447,390,000				$ 337,353,000				$ 447,390,000	$ 337,353,000
Investments in and advances to unconsolidated affiliates	184,352,000				181,322,000				184,352,000	181,322,000
Total assets	2,732,600,000				2,264,957,000				2,732,600,000	2,264,957,000
Other liabilities	25,148,000				18,265,000				25,148,000	18,265,000
Total liabilities and equity	2,732,600,000				2,264,957,000				2,732,600,000	2,264,957,000
Company's share of distributions in excess of income and investments in unconsolidated affiliates	(12,564,000)				(8,701,000)				(12,564,000)	(8,701,000)
Combined and Condensed Statements of Operations [Abstract]
Total revenues	51,156,000	47,660,000	49,511,000	46,685,000	44,102,000	41,085,000	40,808,000	42,291,000	195,012,000	168,286,000	114,987,000
Operating and other expenses									(128,749,000)	(112,407,000)	(87,232,000)
Equity in (losses) earnings of unconsolidated affiliates									8,723,000	12,382,000	550,000
Depreciation and amortization									(49,645,000)	(40,299,000)	(27,888,000)
Loss on debt extinguishment									(335,000)	(765,000)	(198,000)
Income from continuing operations									150,924,000	26,503,000	9,267,000
Unconsolidated Affiliates [Member]
Combined and Condensed Balance Sheets
Rental property, net	387,739,000				380,268,000				387,739,000	380,268,000
Real estate under development	60,476,000				5,573,000				60,476,000	5,573,000
Investments in and advances to unconsolidated affiliates	11,154,000				63,745,000				11,154,000	63,745,000
Other assets	62,862,000				66,895,000				62,862,000	66,895,000
Total assets	522,231,000				516,481,000				522,231,000	516,481,000
Mortgage notes payable	315,897,000				265,982,000				315,897,000	265,982,000
Other liabilities	66,116,000				43,733,000				66,116,000	43,733,000
Partners’ equity	140,218,000				206,766,000				140,218,000	206,766,000
Total liabilities and equity	522,231,000				516,481,000				522,231,000	516,481,000
Combined and Condensed Statements of Operations [Abstract]
Total revenues									44,422,000	51,638,000	49,729,000
Operating and other expenses									(17,069,000)	(18,700,000)	(18,919,000)
Interest expense									(9,363,000)	(8,943,000)	(18,547,000)
Equity in (losses) earnings of unconsolidated affiliates									(328,000)	13,651,000	583,000
Depreciation and amortization									(10,967,000)	(10,599,000)	(9,551,000)
Loss on debt extinguishment									(187,000)	0	(293,000)
Gain on disposition of properties									142,615,000	0	3,402,000
Income from continuing operations									149,123,000	27,047,000	6,404,000
Operating Partnership, as General Partner or Managing Member [Member]
Combined and Condensed Statements of Operations [Abstract]
Equity in (losses) earnings of unconsolidated affiliates									111,578,000	12,382,000	1,579,000
Company’s share of net income									111,970,000	12,774,000	1,971,000
Amortization of excess investment									(392,000)	(392,000)	(392,000)
KLA/Mervyns LLC Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	10.50%								10.50%
KLA A Markets LLC Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	20.00%								20.00%
KA-Shopko LLC [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	20.00%								20.00%
Marsh and Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	20.00%								20.00%
KLAC Rex Venture LLC [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	13.30%								13.30%
Mervyns I and Mervyns II [Member] | KLA/Mervyns LLC Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	5.80%								5.80%
Mervyns II [Member] | KLA A Markets LLC Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	6.00%								6.00%
Mervyns II [Member] | KLAC Rex Venture LLC [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	13.30%								13.30%
Fund II [Member] | KA-Shopko LLC [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	2.00%								2.00%
Fund II [Member] | Marsh and Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	3.30%								3.30%
KLA/Mervyns LLC [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	10.50%								10.50%
KLA/Mervyns LLC [Member] | Mervyns I and Mervyns II [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	5.80%								5.80%
KLA A Markets LLC [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	18.90%								18.90%
KLA A Markets LLC [Member] | Mervyns II [Member]
Schedule of Equity Method Investments [Line Items]
Acadia Investors Ownership Percentage	5.70%								5.70%
Core Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Purchase Price									473,200,000
Combined and Condensed Statements of Operations [Abstract]
Total revenues									125,022,000	110,355,000	70,400,000
Equity in (losses) earnings of unconsolidated affiliates									(77,000)	(99,000)	262,000
Depreciation and amortization									(35,875,000)	(28,989,000)	(17,065,000)
Loss on debt extinguishment									(3,000)	(309,000)	0
Income from continuing operations									16,497,000	4,000	(1,102,000)
Core Portfolio [Member] | Chicago, Illinois [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	88.43%								88.43%
Square footage of real estate property (in square feet)	87,000								87,000
Core Portfolio [Member] | White Plains, New York [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	49.00%								49.00%
Square footage of real estate property (in square feet)	311,000								311,000
Core Portfolio [Member] | Georgetown Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	50.00%								50.00%
Square footage of real estate property (in square feet)	28,000								28,000
Core Portfolio [Member] | Route 202 Shopping Center [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	22.22%								22.22%
Square footage of real estate property (in square feet)	20,000								20,000
Opportunity Funds [Member]
Schedule of Equity Method Investments [Line Items]
Number of unaffiliated partners									2
Combined and Condensed Statements of Operations [Abstract]
Total revenues									54,659,000	46,131,000	36,560,000
Equity in (losses) earnings of unconsolidated affiliates									8,800,000	12,481,000	288,000
Depreciation and amortization									(13,770,000)	(11,310,000)	(10,823,000)
Loss on debt extinguishment									(332,000)	(456,000)	(198,000)
Income from continuing operations									120,011,000	14,699,000	2,747,000
Opportunity Funds [Member] | RCP Venture [Member]
Schedule of Equity Method Investments [Line Items]
Distributions, cost method investments									149,622,000
Combined and Condensed Balance Sheets
Investments in and advances to unconsolidated affiliates	63,216,000								63,216,000
Opportunity Funds [Member] | RCP Venture [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Distributions, cost method investments									32,142,000
Combined and Condensed Balance Sheets
Investments in and advances to unconsolidated affiliates	12,070,000								12,070,000
Opportunity Funds [Member] | Mervyns I and Mervyns II [Member] | KLA/Mervyns LLC Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	7,547,000								7,547,000
Distributions, cost method investments									5,789,000
Opportunity Funds [Member] | Mervyns I and Mervyns II [Member] | KLA/Mervyns LLC Add-On Investments [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	1,252,000								1,252,000
Distributions, cost method investments									1,284,000
Opportunity Funds [Member] | Mervyns II [Member] | KLA A Markets LLC Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	2,416,000								2,416,000
Distributions, cost method investments									4,864,000
Opportunity Funds [Member] | Mervyns II [Member] | KLA A Markets LLC Add-On Investments [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	388,000								388,000
Distributions, cost method investments									972,000
Opportunity Funds [Member] | Mervyns II [Member] | KLAC Rex Venture LLC [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	2,701,000								2,701,000
Distributions, cost method investments									3,729,000
Opportunity Funds [Member] | Mervyns II [Member] | KLAC Rex Venture LLC [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	535,000								535,000
Distributions, cost method investments									747,000
Opportunity Funds [Member] | Fund II [Member] | KA-Shopko LLC [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	1,110,000								1,110,000
Distributions, cost method investments									2,460,000
Opportunity Funds [Member] | Fund II [Member] | KA-Shopko LLC [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	222,000								222,000
Distributions, cost method investments									492,000
Opportunity Funds [Member] | Fund II [Member] | Marsh and Add-On Investments [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	2,667,000								2,667,000
Distributions, cost method investments									2,639,000
Opportunity Funds [Member] | Fund II [Member] | Marsh and Add-On Investments [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, cost method investments	533,000								533,000
Distributions, cost method investments									528,000
Opportunity Funds [Member] | KLA/Mervyns LLC [Member] | Mervyns I and Mervyns II [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, equity method investment	26,058,000								26,058,000
Distributions, equity method investments									48,547,000
Opportunity Funds [Member] | KLA/Mervyns LLC [Member] | Mervyns I and Mervyns II [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, equity method investment	4,901,000								4,901,000
Distributions, equity method investments									11,801,000
Opportunity Funds [Member] | KLA A Markets LLC [Member] | Mervyns II [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, equity method investment	20,717,000								20,717,000
Distributions, equity method investments									81,594,000
Opportunity Funds [Member] | KLA A Markets LLC [Member] | Mervyns II [Member] | Operating Partnership, as General Partner or Managing Member [Member]
Schedule of Equity Method Investments [Line Items]
Invested Capital and Advances, equity method investment	4,239,000								4,239,000
Distributions, equity method investments									16,318,000
Fund IV [Member]
Schedule of Equity Method Investments [Line Items]
Purchase Price									106,600,000
Fund IV [Member] | Savannah, Georgia [Member]
Schedule of Equity Method Investments [Line Items]
Loan commitment	69,000,000								69,000,000
Number of properties acquired									24
Purchase Price									33,900,000
Combined and Condensed Balance Sheets
Investments in and advances to unconsolidated affiliates	8,100,000								8,100,000
Fund IV [Member] | Savannah, Georgia [Member] | RCP Venture [Member]
Schedule of Equity Method Investments [Line Items]
Loan commitment	28,400,000								28,400,000
Fund IV [Member] | Bear, Delaware [Member]
Combined and Condensed Balance Sheets
Investments in and advances to unconsolidated affiliates	25,400,000								25,400,000
Fund IV [Member] | Miami, Florida [Member] | Lincoln Road Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Investment, aggregate sales price		200,200,000
Gain (loss) on sale of investments		54,600,000
Fund III [Member] | Miami, Florida [Member] | Lincoln Road Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Number of properties sold		3
Investment, aggregate sales price		141,800,000
Gain (loss) on sale of investments		$ 86,600,000