SENIOR NOTES PAYABLE AND OTHER DEBT (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Feb. 28, 2013	Dec. 31, 2012
Debt instruments
Total	$ 9,359,018		$ 8,186,315
Capital lease obligations	0		142,412
Unamortized fair value adjustment	80,320		111,623
Unamortized discounts	(26,020)		(26,704)
Senior notes payable and other debt	9,413,318		8,413,646
Unsecured revolving credit facilities
Debt instruments
Total	447,970		540,727
6.25% Senior Notes due 2013
Debt instruments
Total	0		269,850
Interest rate (as a percent)		6.25%	6.25%
Unsecured term loan due 2015
Debt instruments
Total	125,739		130,336
3.125% Senior Notes due 2015
Debt instruments
Total	400,000		400,000
Interest rate (as a percent)	3.125%		3.125%
6% Senior Notes due 2015
Debt instruments
Total	234,420		234,420
Interest rate (as a percent)	6.00%		6.00%
One Point Five Five Percent Senior Notes, Due 2016 [Member]
Debt instruments
Total	550,000
Interest rate (as a percent)	1.55%
Unsecured term loan due 2017
Debt instruments
Total	375,000		375,000
Unsecured term loan due 2018
Debt instruments
Total	180,000		180,000
2.00% Senior Notes due 2018
Debt instruments
Total	700,000		700,000
Interest rate (as a percent)	2.00%		2.00%
4.00% senior notes due 2019
Debt instruments
Total	600,000		600,000
Interest rate (as a percent)	4.00%		4.00%
2.700% Senior Notes due 2020
Debt instruments
Total	500,000		0
Interest rate (as a percent)	2.70%
4.750% Senior Notes due 2021
Debt instruments
Total	700,000		700,000
Interest rate (as a percent)	4.75%		4.75%
4.25% senior notes due 2022
Debt instruments
Total	600,000		600,000
Interest rate (as a percent)	4.25%		4.25%
3.25% senior notes due 2022
Debt instruments
Total	500,000		500,000
Interest rate (as a percent)	3.25%		3.25%
6.90% Senior Notes due 2037
Debt instruments
Total	52,400		52,400
Interest rate (as a percent)	6.90%		6.90%
6.59% Senior Notes due 2038
Debt instruments
Total	22,973		22,973
Interest rate (as a percent)	6.59%		6.59%
5.45% Senior Notes due 2043
Debt instruments
Total	258,750		0
Interest rate (as a percent)	5.45%
Mortgage loans and other
Debt instruments
Total	2,811,766		2,880,609
Unsecured term loan
Debt instruments
Total	$ 500,000