SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 reportable_segments	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Number of Reportable Segments									4
Revenues	$ 37,141	$ 34,648	$ 32,723	$ 29,913	$ 28,783	$ 27,356	$ 29,206	$ 29,733	$ 134,425	$ 115,078	$ 116,390
Property operating expenses, other operating and real estate taxes									44,700	34,288	33,514
General and administrative expenses									21,532	23,066	20,209
Income before depreciation and amortization									68,193	57,724	62,667
Depreciation and amortization									32,931	25,672	23,419
Interest and other finance expense									28,768	29,632	34,414
Real estate at cost	1,495,742				1,098,761				1,495,742	1,098,761	950,710
Total assets	1,886,379				1,289,436				1,886,379	1,289,436	1,187,380
Acquisition of real estate									241,894	116,408	2,849
Redevelopment and Property Improvement Costs									82,127	61,311	76,295
Other interest income									148	276	406
Equity in earnings of unconsolidated affiliates									1,579	1,555	10,971
Impairment of unconsolidated affiliates									(2,032)	0	0
(Loss) gain on debt extinguishment									(198)	1,268	0
Income tax benefit (provision)									568	(461)	(2,869)
Gain from bargain purchase									0	0	33,805
Impairment of asset									0	(6,925)	0
Reserve for notes receivable									(405)	0	0
Gain on involuntary conversion of asset									2,368	0	0
Gain on sale of property									71,203	46,830	0
Loss on debt extinguishment									(2,541)	0	0
Operating income from discontinued operations									10,720	8,752	3,520
Net income									89,936	53,715	50,667
Net income attributable to noncontrolling interests									(50,230)	(2,160)	(20,610)
Net income attributable to Common Shareholders	21,276	7,581	6,839	4,010	7,887	4,011	30,234	9,423	39,706	51,555	30,057
Core Portfolio [Member]
Segment Reporting Information [Line Items]
Revenues									70,599	57,994	57,084
Property operating expenses, other operating and real estate taxes									21,699	17,087	17,236
General and administrative expenses									22,817	24,226	22,439
Income before depreciation and amortization									26,083	16,681	17,409
Depreciation and amortization									18,316	14,206	13,798
Interest and other finance expense									15,229	15,967	18,036
Real estate at cost	744,880				499,872				744,880	499,872	441,714
Total assets	877,926				633,345				877,926	633,345	574,497
Acquisition of real estate									175,556	60,305	0
Redevelopment and Property Improvement Costs									5,381	12,266	4,137
Opportunity Funds [Member]
Segment Reporting Information [Line Items]
Revenues									54,286	43,994	38,721
Property operating expenses, other operating and real estate taxes									26,001	19,618	17,814
General and administrative expenses									14,373	16,658	13,577
Income before depreciation and amortization									13,912	7,718	7,330
Depreciation and amortization									15,594	12,361	10,061
Interest and other finance expense									12,910	12,672	16,820
Real estate at cost	764,471				614,321				764,471	614,321	522,345
Total assets	1,017,870				730,029				1,017,870	730,029	629,292
Acquisition of real estate									66,338	56,103	2,849
Redevelopment and Property Improvement Costs									78,265	51,128	74,460
Notes Receivable [Member]
Segment Reporting Information [Line Items]
Revenues									7,973	11,429	19,161
Property operating expenses, other operating and real estate taxes									0	0	0
General and administrative expenses									0	0	0
Income before depreciation and amortization									7,973	11,429	19,161
Depreciation and amortization									0	0	0
Interest and other finance expense									0	0	0
Real estate at cost	0				0				0	0	0
Total assets	129,278				59,989				129,278	59,989	89,202
Acquisition of real estate									0	0	0
Redevelopment and Property Improvement Costs									0	0	0
Other [Member]
Segment Reporting Information [Line Items]
Revenues									22,947	25,782	22,479
Property operating expenses, other operating and real estate taxes									0	0	0
General and administrative expenses									0	0	0
Income before depreciation and amortization									22,947	25,782	22,479
Depreciation and amortization									0	0	0
Interest and other finance expense									0	0	0
Real estate at cost	0				0				0	0	0
Total assets	0				0				0	0	0
Acquisition of real estate									0	0	0
Redevelopment and Property Improvement Costs									0	0	0
Amounts Eliminated in Consolidation [Member]
Segment Reporting Information [Line Items]
Revenues									(21,380)	(24,121)	(21,055)
Property operating expenses, other operating and real estate taxes									(3,000)	(2,417)	(1,536)
General and administrative expenses									(15,658)	(17,818)	(15,807)
Income before depreciation and amortization									(2,722)	(3,886)	(3,712)
Depreciation and amortization									(979)	(895)	(440)
Interest and other finance expense									629	993	(442)
Real estate at cost	(13,609)				(15,432)				(13,609)	(15,432)	(13,349)
Total assets	(138,695)				(133,927)				(138,695)	(133,927)	(105,611)
Acquisition of real estate									0	0	0
Redevelopment and Property Improvement Costs									$ (1,519)	$ (2,083)	$ (2,302)