INVESTMENTS IN JOINT VENTURES (Schedule of New Joint Ventures) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 Property	Dec. 31, 2012 Property	Dec. 31, 2011 Property
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	67	20	15
Payments to acquired equity method investments, new investments	$ 265,500,000	$ 149,500,000	$ 63,600,000
Multifamily Properties [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	2	5	8
Payments to acquired equity method investments, new investments	9,100,000	22,900,000	19,900,000
Multifamily Properties [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	1	2	0
Payments to acquired equity method investments, new investments	58,000,000	34,300,000	0
Residential Real Estate [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	3	2	2
Payments to acquired equity method investments, new investments	10,000,000	19,600,000	17,900,000
Other Investments [Member] | Spain [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	1	0
Payments to acquired equity method investments, new investments	27,200,000	0	0
Commercial [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	4	9	5
Payments to acquired equity method investments, new investments	30,300,000	26,900,000	25,800,000
Commercial [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	14	2	0
Payments to acquired equity method investments, new investments	38,700,000	45,800,000	0
Commercial [Member] | UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Number of Properties in New Joint Ventures	42	0	0
Payments to acquired equity method investments, new investments	$ 92,200,000	$ 0	$ 0