SENIOR NOTES PAYABLE AND OTHER DEBT (Details 3) (USD $)	3 Months Ended		6 Months Ended								1 Months Ended			1 Months Ended	3 Months Ended				1 Months Ended			1 Months Ended			1 Months Ended	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Unsecured term loan	Jun. 30, 2012 Unsecured term loan due 2015	Dec. 31, 2011 Unsecured term loan due 2015	Jun. 30, 2012 Unsecured term loan due 2017	Dec. 31, 2011 Unsecured term loan due 2017	Feb. 29, 2012 4.25% senior notes due 2022	Jun. 30, 2012 4.25% senior notes due 2022	May 31, 2012 4.25% senior notes due 2022	Mar. 31, 2012 6 1/2% Senior Notes due 2016	Mar. 31, 2012 6 1/2% Senior Notes due 2016	Jun. 30, 2012 6 1/2% Senior Notes due 2016	May 31, 2012 6 1/2% Senior Notes due 2016	Dec. 31, 2011 6 1/2% Senior Notes due 2016	Apr. 30, 2012 4.00% senior notes due 2019	Jun. 30, 2012 4.00% senior notes due 2019	Dec. 31, 2011 4.00% senior notes due 2019	Jul. 31, 2011 8 1/4% Senior Notes due 2012	Jun. 30, 2012 8 1/4% Senior Notes due 2012	Dec. 31, 2011 8 1/4% Senior Notes due 2012	May 31, 2012 6 3/4% Senior Notes due 2017	Jun. 30, 2012 6 3/4% Senior Notes due 2017	Dec. 31, 2011 6 3/4% Senior Notes due 2017	Jun. 30, 2012 9% Senior Notes due 2012	May 31, 2012 9% Senior Notes due 2012	Dec. 31, 2011 9% Senior Notes due 2012	Jun. 30, 2012 Mortgage loans	Dec. 31, 2011 Mortgage loans
Debt instruments
Principal amount of debt issued											$ 600,000,000								$ 600,000,000
Interest rate (as a percent)											4.25%	4.25%	4.25%	6.50%	6.50%	6.50%	6.50%	6.50%	4.00%	4.00%	4.00%		8.25%	8.25%	6.75%	6.75%	6.75%	9.00%	9.00%	9.00%
Public Offering Price as a Percent of Par											99.214%								99.489%
Proceeds from issuance of debt											595,300,000								596,900,000
Principal amount of debt redeemed														200,000,000								73,000,000			225,000,000
Senior Note Redemption Price as a Percent of Par														103.25%	103.25%										103.375%
Repayments of senior debt														206,500,000											232,600,000
Net loss on extinguishment of debt	9,989,000	6,000	39,533,000	16,526,000											29,700,000											10,000,000
Principal amount outstanding	$ 6,960,719,000		$ 6,960,719,000		$ 6,180,443,000	$ 500,000,000	$ 127,378,000	$ 126,875,000	$ 375,000,000	$ 375,000,000		$ 600,000,000						$ 200,000,000		$ 600,000,000			$ 72,950,000	$ 72,950,000			$ 225,000,000			$ 82,433,000	$ 23,600,000	$ 14,600,000