SHARE INCENTIVE PLAN Share Incentive Plan (Details) (USD $)	12 Months Ended						12 Months Ended			1 Months Ended		0 Months Ended	12 Months Ended	1 Months Ended				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2003	Dec. 31, 2011 Trustee [Member]	Mar. 22, 2011 Officer [Member]	Dec. 31, 2011 LTIP Units and Restricted Stock [Member]	Dec. 31, 2010 LTIP Units and Restricted Stock [Member]	Dec. 31, 2009 LTIP Units and Restricted Stock [Member]	Mar. 22, 2011 LTIP Units [Member] Officer [Member]	Mar. 22, 2011 LTIP Units [Member] Other Employees [Member]	May 10, 2011 Restricted Stock [Member] Trustee [Member]	Dec. 31, 2011 Restricted Stock [Member] Trustee [Member]	Mar. 22, 2011 Restricted Stock [Member] Officer [Member]	Mar. 22, 2011 Restricted Stock [Member] Other Employees [Member]	Dec. 31, 2003 2003 Plan [Member]	Dec. 31, 2006 2006 Plan [Member]	Dec. 31, 2009 Long Term Investment Alignment Program [Member] Senior Executives [Member]	Dec. 31, 2011 Long Term Investment Alignment Program [Member] Senior Executives [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum Equivalent Value of Common Shares a Participant Can be Awarded																1,000,000	500,000
Minimum Options Exercise Price as a Percentage of the Fair Market Value of the Common Shares				100.00%
Discount on Shares Issued Relating to Conversion of Senior Managements Cash Bonus Percent				25.00%
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures										431,248	164	22,154		210	9,584
Percent of Awards Issued to Officers Subject to Performance Measures						11.00%
Total Value of Restricted Shares and LTIP Units as of the Grant Date							$ 8,400,000
Share compensation expense	4,299,000	4,104,000	3,969,000				2,400,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	9,400,000						6,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value							$ 19.08	$ 16.73	$ 10.31
Long Term Incentive and Share Based Compensation Expense							4,000,000	3,800,000	3,700,000
Shares Granted to Trustees for Trustee Fees Vesting on One Year Anniversary of Grant Date													10,279
Shares Granted to Trustees for Trustee Fees Begin Vesting on Two Year Anniversary of Grant Date													11,875
Annual Vesting Rate of Shares Granted to Trustees That Begin Vesting on the Second Anniversary of Grant Date													33.00%
Trustee Fees	$ 200,000
Max Percentage of Future Fund III Promote That May be Awarded to Senior Executives																		25.00%
Percent of Units Awarded																			71.00%
Options Outstanding and Vested to Officers and Employees	101,283
Options Outstanding and Vested to Non Employee Turstees					49,000