SENIOR NOTES PAYABLE AND OTHER DEBT (Details) (USD $) In Thousands, unless otherwise specified																																						1 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Unsecured revolving credit facilities	Dec. 31, 2012 Unsecured revolving credit facilities	Jun. 30, 2013 6.25% Senior Notes due 2013	Feb. 28, 2013 6.25% Senior Notes due 2013	Dec. 31, 2012 6.25% Senior Notes due 2013	Jun. 30, 2013 Unsecured term loan due 2015	Dec. 31, 2012 Unsecured term loan due 2015	Jun. 30, 2013 3.125% Senior Notes due 2015	Dec. 31, 2012 3.125% Senior Notes due 2015	Jun. 30, 2013 6% Senior Notes due 2015	Dec. 31, 2012 6% Senior Notes due 2015	Jun. 30, 2013 Unsecured term loan due 2017	Dec. 31, 2012 Unsecured term loan due 2017	Jun. 30, 2013 Unsecured term loan due 2018	Dec. 31, 2012 Unsecured term loan due 2018	Jun. 30, 2013 2.00% Senior Notes due 2018	Dec. 31, 2012 2.00% Senior Notes due 2018	Jun. 30, 2013 4.00% senior notes due 2019	Dec. 31, 2012 4.00% senior notes due 2019	Jun. 30, 2013 2.700% Senior Notes due 2020	Dec. 31, 2012 2.700% Senior Notes due 2020	Jun. 30, 2013 4.750% Senior Notes due 2021	Dec. 31, 2012 4.750% Senior Notes due 2021	Jun. 30, 2013 4.25% senior notes due 2022	Dec. 31, 2012 4.25% senior notes due 2022	Jun. 30, 2013 3.25% senior notes due 2022	Dec. 31, 2012 3.25% senior notes due 2022	Jun. 30, 2013 6.90% Senior Notes due 2037	Dec. 31, 2012 6.90% Senior Notes due 2037	Jun. 30, 2013 6.59% Senior Notes due 2038	Dec. 31, 2012 6.59% Senior Notes due 2038	Jun. 30, 2013 5.45% Senior Notes due 2043	Dec. 31, 2012 5.45% Senior Notes due 2043	Jun. 30, 2013 Mortgage loans and other	Dec. 31, 2012 Mortgage loans and other	Jul. 25, 2013 Mortgage loans and other Subsequent Event	Jun. 30, 2013 Unsecured term loan
Debt instruments
Total	$ 8,362,709	$ 8,186,315	$ 259,616	$ 540,727	$ 0		$ 269,850	$ 123,306	$ 130,336	$ 400,000	$ 400,000	$ 234,420	$ 234,420	$ 375,000	$ 375,000	$ 180,000	$ 180,000	$ 700,000	$ 700,000	$ 600,000	$ 600,000	$ 500,000	$ 0	$ 700,000	$ 700,000	$ 600,000	$ 600,000	$ 500,000	$ 500,000	$ 52,400	$ 52,400	$ 22,973	$ 22,973	$ 258,750	$ 0	$ 2,856,244	$ 2,880,609		$ 500,000
Interest rate (as a percent)						6.25%	6.25%			3.125%	3.125%	6.00%	6.00%					2.00%	2.00%	4.00%	4.00%	2.70%		4.75%	4.75%	4.25%	4.25%	3.25%	3.25%	6.90%	6.90%	6.59%	6.59%	5.45%
Capital lease obligations	0	142,412
Unamortized fair value adjustment	82,648	111,623
Unamortized discounts	(25,284)	(26,704)
Senior notes payable and other debt	8,420,073	8,413,646
Repayment of loans outstanding																																						$ 126,200