SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS Noncontrolling Interest (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance				$ 447,459,000					$ 447,459,000
Distributions declared	$ 0.23	$ 0.21	$ 0.21	$ 0.21	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.86	$ 0.72	$ 0.72
Net income for the period January 1 through December 31, 2013									(4,525,000)	(50,230,000)	(2,160,000)
Conversion of 92,514 OP Units to Common Shares by limited partners of the Operating Partnership										0	0
Issuance of OP Units to acquire real estate									33,300,000	2,279,000	0
Other comprehensive income - unrealized loss on valuation of swap agreements									3,610,000	(3,519,000)	(5,611,000)
Reclassification of realized interest on swap agreements									2,892,000	2,268,000	3,081,000
Noncontrolling Interest contributions									49,324,000	172,228,000	117,945,000
Noncontrolling interest distributions and other reductions									(87,688,000)	(160,663,000)	(7,697,000)
Employee Long-term Incentive Plan Unit Awards									7,672,000	6,691,000	6,122,000
Balance	417,352,000				447,459,000				417,352,000	447,459,000
Limited Partners' Capital Account, Units Issued and Converted	92,514								92,514
Share-based Compensation, Units converted from Series A Preferred OP Units	185,600								185,600
Denominator for Series A Preferred OP Unit Conversion	7.50								7.50
LTIP Units [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based Compensation, Units Outstanding	1,368,086				1,109,727				1,368,086	1,109,727
Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Per Unit Conversion Amount, Series A Preferred OP Units	22.50								22.50
Per Unit Conversion Annual Rate, Series A Preferred OP Units	9.00%								9.00%
Limited Partners' Capital Account, Units Issued and Converted	1,392								1,392
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of 92,514 OP Units to Common Shares by limited partners of the Operating Partnership									(1,548,000)	(5,880,000)	(56,000)
Issuance of OP Units to acquire real estate									33,300,000	2,279,000
Other comprehensive income - unrealized loss on valuation of swap agreements									69,000	(1,704,000)	(2,150,000)
Reclassification of realized interest on swap agreements									994,000	847,000	676,000
Noncontrolling Interest contributions									49,324,000	172,228,000	117,945,000
Noncontrolling interest distributions and other reductions									(87,688,000)	(160,663,000)	(7,697,000)
Employee Long-term Incentive Plan Unit Awards									6,530,000	6,025,000	5,991,000
Noncontrolling Interests | Partially-Owned Affiliates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance				435,665,000					435,665,000
Distributions declared of $0.86 per Common OP Unit									0
Net income for the period January 1 through December 31, 2013									4,033,000
Conversion of 92,514 OP Units to Common Shares by limited partners of the Operating Partnership									0
Issuance of LTIP Unit awards to employees									(33,949,000)
Issuance of OP Units to acquire real estate									0
Other comprehensive income - unrealized loss on valuation of swap agreements									46,000
Reclassification of realized interest on swap agreements									973,000
Noncontrolling Interest contributions									49,324,000
Noncontrolling interest distributions and other reductions									(87,688,000)
Employee Long-term Incentive Plan Unit Awards									0
Balance	368,404,000								368,404,000
Operating Partnership, as General Partner or Managing Member [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units	1,457,467				284,097				1,457,467	284,097
Operating Partnership, as General Partner or Managing Member [Member] | Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units	188				188				188	188
Limited Partners' Capital Account, Value Per Unit	1,000				1,000				1,000	1,000
Operating Partnership, as General Partner or Managing Member [Member] | Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance				11,794,000					11,794,000
Distributions declared of $0.86 per Common OP Unit									(1,664,000)
Net income for the period January 1 through December 31, 2013									492,000
Conversion of 92,514 OP Units to Common Shares by limited partners of the Operating Partnership									(1,548,000)
Issuance of LTIP Unit awards to employees									0
Issuance of OP Units to acquire real estate									33,300,000
Other comprehensive income - unrealized loss on valuation of swap agreements									23,000
Reclassification of realized interest on swap agreements									21,000
Noncontrolling Interest contributions									0
Noncontrolling interest distributions and other reductions									0
Employee Long-term Incentive Plan Unit Awards									6,530,000
Balance	$ 48,948,000								$ 48,948,000