SENIOR NOTES PAYABLE AND OTHER DEBT (Details) (USD $)																																												1 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Unsecured Line of Credit [Member]	Dec. 31, 2013 Unsecured Line of Credit [Member]	Mar. 31, 2014 Unsecured revolving credit facilities	Dec. 31, 2013 Unsecured revolving credit facilities	Mar. 31, 2014 6.25% Senior Notes due 2013	Dec. 31, 2013 6.25% Senior Notes due 2013	Mar. 31, 2014 3.125% Senior Notes due 2015	Dec. 31, 2013 3.125% Senior Notes due 2015	Mar. 31, 2014 6% Senior Notes due 2015	Dec. 31, 2013 6% Senior Notes due 2015	Mar. 31, 2014 1.55% Senior Notes due 2016	Dec. 31, 2013 1.55% Senior Notes due 2016	Mar. 31, 2014 2.00% Senior Notes due 2018	Dec. 31, 2013 2.00% Senior Notes due 2018	Mar. 31, 2014 Unsecured Term Loan Due 2018 Number Two [Member]	Dec. 31, 2013 Unsecured Term Loan Due 2018 Number Two [Member]	Mar. 31, 2014 Unsecured Term Loan Due 2019 [Member]	Dec. 31, 2013 Unsecured Term Loan Due 2019 [Member]	Mar. 31, 2014 4.00% senior notes due 2019	Dec. 31, 2013 4.00% senior notes due 2019	Mar. 31, 2014 2.700% Senior Notes due 2020	Dec. 31, 2013 2.700% Senior Notes due 2020	Mar. 31, 2014 4.750% Senior Notes due 2021	Dec. 31, 2013 4.750% Senior Notes due 2021	Mar. 31, 2014 4.25% senior notes due 2022	Dec. 31, 2013 4.25% senior notes due 2022	Mar. 31, 2014 3.25% senior notes due 2022	Dec. 31, 2013 3.25% senior notes due 2022	Mar. 31, 2014 6.90% Senior Notes due 2037	Dec. 31, 2013 6.90% Senior Notes due 2037	Mar. 31, 2014 6.59% Senior Notes due 2038	Dec. 31, 2013 6.59% Senior Notes due 2038	Mar. 31, 2014 5.45% Senior Notes due 2043	Dec. 31, 2013 5.45% Senior Notes due 2043	Mar. 31, 2014 Five Point Seven Zero Percent Senior Notes, Due 2043 [Member]	Dec. 31, 2013 Five Point Seven Zero Percent Senior Notes, Due 2043 [Member]	Mar. 31, 2014 Mortgage loans and other	Dec. 31, 2013 Mortgage loans and other	Mar. 31, 2014 Unsecured term loan	Dec. 31, 2013 Mortgage Loans Held for Sale [Member]	Mar. 31, 2014 Canada, Dollars Unsecured term loan	Dec. 31, 2013 London Interbank Offered Rate (LIBOR) [Member] Unsecured revolving credit facilities	Dec. 31, 2013 London Interbank Offered Rate (LIBOR) [Member] Unsecured Term Loan Due 2018 Number Two [Member]
Debt instruments
Line of Credit Facility, Current Borrowing Capacity						$ 2,000,000,000												$ 200,000,000		$ 800,000,000
Line of Credit Facility, Maximum Borrowing Capacity				3,500,000,000
Amount outstanding			192,300,000		559,300,000
Total Maturities	9,442,636,000	9,320,477,000			559,299,000	376,343,000			400,000,000	400,000,000	234,420,000	234,420,000	550,000,000	550,000,000	700,000,000	700,000,000	200,000,000	200,000,000	796,165,000	800,702,000	600,000,000	600,000,000	500,000,000	500,000,000	700,000,000	700,000,000	600,000,000	600,000,000	500,000,000	500,000,000	52,400,000	52,400,000	22,973,000	22,973,000	258,750,000	258,750,000	300,000,000	300,000,000	2,468,629,000	2,524,889,000	1,000,000,000	13,100,000	112,600,000
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%	2.70%	4.75%	4.75%	4.25%	4.25%	3.25%	3.25%	6.90%	6.90%	6.59%	6.59%	5.45%	5.45%
Unamortized fair value adjustment	62,578,000	69,611,000
Unamortized discounts	(24,163,000)	(25,096,000)
Senior notes payable and other debt	$ 9,481,051,000	$ 9,364,992,000
Debt Instrument, Description of Variable Rate Basis																																												LIBOR	LIBOR
Debt Instrument, Basis Spread on Variable Rate																																												1.00%	1.05%