SENIOR NOTES PAYABLE AND OTHER DEBT (Details) (USD $)	Mar. 31, 2012 property	Dec. 31, 2011 property	Mar. 31, 2012 Unsecured revolving credit facilities	Dec. 31, 2011 Unsecured revolving credit facilities	Mar. 31, 2012 9% Senior Notes due 2012	Dec. 31, 2011 9% Senior Notes due 2012	Mar. 31, 2012 8 1/4% Senior Notes due 2012	Dec. 31, 2011 8 1/4% Senior Notes due 2012	Mar. 31, 2012 Unsecured term loan due 2013	Dec. 31, 2011 Unsecured term loan due 2013	Mar. 31, 2012 6.25% Senior Notes due 2013	Dec. 31, 2011 6.25% Senior Notes due 2013	Mar. 31, 2012 Unsecured term loan due 2015	Dec. 31, 2011 Unsecured term loan due 2015	Mar. 31, 2012 3.125% Senior Notes due 2015	Dec. 31, 2011 3.125% Senior Notes due 2015	Mar. 31, 2012 6% Senior Notes due 2015	Dec. 31, 2011 6% Senior Notes due 2015	Mar. 31, 2012 6 1/2% Senior Notes due 2016	Dec. 31, 2011 6 1/2% Senior Notes due 2016	Mar. 31, 2012 Unsecured term loan due 2017	Dec. 31, 2011 Unsecured term loan due 2017	Apr. 30, 2012 6 3/4% Senior Notes due 2017	Mar. 31, 2012 6 3/4% Senior Notes due 2017	Dec. 31, 2011 6 3/4% Senior Notes due 2017	Mar. 31, 2012 4.750% Senior Notes due 2021	Dec. 31, 2011 4.750% Senior Notes due 2021	Mar. 31, 2012 6.90% Senior Notes due 2037	Dec. 31, 2011 6.90% Senior Notes due 2037	Mar. 31, 2012 6.59% Senior Notes due 2038	Dec. 31, 2011 6.59% Senior Notes due 2038	Mar. 31, 2012 Mortgage loans and other	Dec. 31, 2011 Mortgage loans and other	Mar. 31, 2012 4.25% senior notes due 2022	Feb. 29, 2012 4.25% senior notes due 2022	Dec. 31, 2011 4.25% senior notes due 2022
Debt instruments
Total	$ 6,179,076,000	$ 6,180,443,000	$ 73,419,000	$ 455,578,000	$ 82,433,000	$ 82,433,000	$ 72,950,000	$ 72,950,000	$ 200,000,000	$ 200,000,000	$ 269,850,000	$ 269,850,000	$ 129,721,000	$ 126,875,000	$ 400,000,000	$ 400,000,000	$ 234,420,000	$ 234,420,000	$ 0	$ 200,000,000	$ 375,000,000	$ 375,000,000		$ 225,000,000	$ 225,000,000	$ 700,000,000	$ 700,000,000	$ 52,400,000	$ 52,400,000	$ 22,973,000	$ 22,973,000	$ 2,740,910,000	$ 2,762,964,000	$ 600,000,000		$ 0
Interest rate (as a percent)					9.00%	9.00%	8.25%	8.25%			6.25%	6.25%			3.125%	3.125%	6.00%	6.00%	6.50%	6.50%			6.75%	6.75%	6.75%	4.75%	4.75%	6.90%	6.90%	6.59%	6.59%			4.25%	4.25%
Capital lease obligations	142,857,000	143,006,000
Unamortized fair value adjustment	131,985,000	144,923,000
Unamortized commission fees and discounts	(23,554,000)	(39,256,000)
Senior notes payable and other debt	6,430,364,000	6,429,116,000
Joint venture partners' share of total debt	64,400,000	46,600,000
Number of properties owned through consolidated joint ventures with mortgage debt	9	8
Debt related to investments in unconsolidated entities	$ 128,400,000	$ 131,500,000