INVESTMENTS IN AND ADVANCES TO UNCONSOLIDATED AFFILIATES (Details) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended																3 Months Ended		6 Months Ended					3 Months Ended		6 Months Ended															6 Months Ended				3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Unconsolidated Affiliates	Jun. 30, 2011 Unconsolidated Affiliates	Jun. 30, 2012 Unconsolidated Affiliates	Jun. 30, 2011 Unconsolidated Affiliates	Dec. 31, 2011 Unconsolidated Affiliates	Jun. 30, 2012 Operating Partnership, as General Partner or Managing Member	Jun. 30, 2011 Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Operating Partnership, as General Partner or Managing Member	Jun. 30, 2011 Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 KLA/Mervyns LLC Add-On Investments	Jun. 30, 2012 KLA A Markets LLC Add-On Investments	Jun. 30, 2012 KA-Shopko LLC	Jun. 30, 2012 Marsh and Add-On Investments	Jun. 30, 2012 KLAC Rex Venture LLC	Jun. 30, 2012 Mervyns I and Mervyns II KLA/Mervyns LLC Add-On Investments	Jun. 30, 2012 Mervyns II KLA A Markets LLC Add-On Investments	Jun. 30, 2012 Mervyns II KLAC Rex Venture LLC	Jun. 30, 2012 Fund II KA-Shopko LLC	Jun. 30, 2012 Fund II Marsh and Add-On Investments	Jun. 30, 2012 KLA/Mervyns LLC	Jun. 30, 2012 KLA/Mervyns LLC Mervyns I and Mervyns II	Jun. 30, 2012 KLA A Markets LLC	Jun. 30, 2012 KLA A Markets LLC Mervyns II	Jun. 30, 2012 Core Portfolio	Jun. 30, 2011 Core Portfolio	Jun. 30, 2012 Core Portfolio	Jun. 30, 2011 Core Portfolio	Jun. 30, 2012 Core Portfolio Brandywine Portfolio sqft	Jun. 30, 2012 Core Portfolio Crossroads sqft	Jun. 30, 2012 Core Portfolio Georgetown Portfolio sqft	Jun. 30, 2012 Opportunity Funds	Jun. 30, 2011 Opportunity Funds	Jun. 30, 2012 Opportunity Funds	Jun. 30, 2011 Opportunity Funds	Jun. 30, 2012 Opportunity Funds RCP Venture	Jun. 30, 2012 Opportunity Funds RCP Venture Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds Mervyns I and Mervyns II KLA/Mervyns LLC Add-On Investments	Jun. 30, 2012 Opportunity Funds Mervyns I and Mervyns II KLA/Mervyns LLC Add-On Investments Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds Mervyns II KLA A Markets LLC Add-On Investments	Jun. 30, 2012 Opportunity Funds Mervyns II KLA A Markets LLC Add-On Investments Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds Mervyns II KLAC Rex Venture LLC	Jun. 30, 2012 Opportunity Funds Mervyns II KLAC Rex Venture LLC Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds Fund II KA-Shopko LLC	Jun. 30, 2012 Opportunity Funds Fund II KA-Shopko LLC Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds Fund II Marsh and Add-On Investments	Jun. 30, 2012 Opportunity Funds Fund II Marsh and Add-On Investments Operating Partnership, as General Partner or Managing Member	Jun. 30, 2010 Opportunity Funds Fund III locations	Jun. 30, 2012 Opportunity Funds KLA/Mervyns LLC Mervyns I and Mervyns II	Jun. 30, 2012 Opportunity Funds KLA/Mervyns LLC Mervyns I and Mervyns II Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds KLA A Markets LLC Mervyns II	Jun. 30, 2012 Opportunity Funds KLA A Markets LLC Mervyns II Operating Partnership, as General Partner or Managing Member	Jun. 30, 2012 Opportunity Funds White Oak Fund III	Jun. 30, 2012 Opportunity Funds Equity Investment Controlled by Unaffiliated Venture Partner Fund III
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage																																	22.20%	49.00%	50.00%																	50.00%					84.00%	49.00%
Square Footage of Real Estate Property (in square feet)																																	1,000,000	311,000	28,000
Noncontrolling Interest, Ownership Percentage by Parent															10.50%	20.00%	20.00%	20.00%	13.30%	5.80%	6.00%	13.30%	2.00%	3.30%	10.50%	5.80%	18.90%	5.70%
Equity Method Investment and Investment Income, Dividends or Distributions	$ 3,900,000										$ 800,000
Equity Method Investments																																																					26,058,000	4,901,000	20,717,000	4,239,000
Equity Method Investment, Dividends or Distributions																																																					45,966,000	11,251,000	81,594,000	16,318,000
Cost Method Investments																																										6,517,000	1,046,000	2,416,000	388,000	2,701,000	535,000	1,108,000	222,000	2,667,000	533,000
Investment Income, Dividend																																								141,817,000	30,528,000	3,558,000	819,000	4,778,000	955,000	1,623,000	325,000	1,659,000	332,000	2,639,000	528,000
Equity Method Investment, Net Sales Proceeds																																																									13,800,000
Equity Method Investment, Note Receivable, Amount																																																										2,200,000
Equity Method Investment, Note Receivable, Interest Rate																																																										6.00%
Number of Locations Owned (in locations)																																																				14
Assets
Rental property, net						274,039,000		274,039,000		280,470,000
Investments in and advances to unconsolidated affiliates	75,495,000		75,495,000		84,568,000	107,667,000		107,667,000		156,421,000																														62,184,000	11,864,000
Other assets						34,679,000		34,679,000		29,587,000
Total assets	1,854,264,000	1,599,601,000	1,854,264,000	1,599,601,000	1,653,319,000	416,385,000		416,385,000		466,478,000																			750,634,000	632,506,000	750,634,000	632,506,000				974,287,000	841,713,000	974,287,000	841,713,000
Liabilities and Equity
Mortgage notes payable						310,090,000		310,090,000		319,425,000
Other liabilities	22,382,000		22,382,000		19,881,000	24,318,000		24,318,000		16,902,000
Partners' equity						81,977,000		81,977,000		130,151,000
Total liabilities and equity	1,854,264,000		1,854,264,000		1,653,319,000	416,385,000		416,385,000		466,478,000
Company's share of distributions in excess of share of income and investments in unconsolidated affiliates	(22,229,000)		(22,229,000)		(21,710,000)
Combined and Condensed Statements of Operations
Total revenues	42,426,000	37,528,000	81,601,000	74,793,000		11,922,000	10,917,000	24,218,000	20,499,000																				17,003,000	14,122,000	32,279,000	28,541,000				16,555,000	14,104,000	31,870,000	26,448,000
Operating and other expenses	28,812,000	25,823,000	56,607,000	50,648,000		4,362,000	3,528,000	8,816,000	7,294,000
Interest expense						4,613,000	4,242,000	9,251,000	8,258,000
Equity in (losses) earnings of unconsolidated affiliates	4,591,000	63,000	4,535,000	(85,000)		6,469,000	(1,370,000)	4,846,000	(412,000)		4,591,000	63,000	4,535,000	(85,000)
Depreciation and amortization	10,147,000	8,301,000	19,215,000	15,870,000		2,371,000	2,376,000	4,643,000	4,245,000																				4,495,000	3,671,000	8,242,000	6,928,000				4,764,000	3,857,000	9,195,000	7,328,000
Gain (Loss) on Disposition of Property						3,402,000	0	3,402,000	0
Income from continuing operations	8,441,000	2,658,000	11,038,000	7,492,000		10,447,000	(599,000)	9,756,000	290,000
Company's share of net income (loss)											4,689,000	160,000	4,731,000	110,000
Amortization of excess investment											$ (98,000)	$ (97,000)	$ (196,000)	$ (195,000)