INVESTMENTS IN JOINT VENTURES INVESTMENTS IN JOINT VENTURES (Schedule of Joint Ventures) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	$ 751,400	$ 543,200
Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	388,900	362,500
Japan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	68,800	102,700
UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	110,800
IRELAND
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	144,300	68,600
Spain [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	26,900
Other United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	11,700	9,400
Multifamily Properties [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	250,300	252,400
Multifamily Properties [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	133,100	126,900
Multifamily Properties [Member] | Japan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	68,800	102,700
Multifamily Properties [Member] | UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Multifamily Properties [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	48,200	22,400
Multifamily Properties [Member] | Spain [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Multifamily Properties [Member] | Other United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	200	400
Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	360,900	154,600
Commercial [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	156,700	141,600
Commercial [Member] | Japan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Commercial [Member] | UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	104,500
Commercial [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	96,100	9,500
Commercial [Member] | Spain [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Commercial [Member] | Other United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	3,600	3,500
Loans [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	56,600	78,500
Loans [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	50,300	41,800
Loans [Member] | Japan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Loans [Member] | UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	6,300
Loans [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0	36,700
Loans [Member] | Spain [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Loans [Member] | Other United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Residential Real Estate [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	48,700	52,000
Residential Real Estate [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	48,400	51,800
Residential Real Estate [Member] | Japan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Residential Real Estate [Member] | UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Residential Real Estate [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Residential Real Estate [Member] | Spain [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Residential Real Estate [Member] | Other United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	300	200
Other Investments [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	34,900	5,700
Other Investments [Member] | Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	400	400
Other Investments [Member] | Japan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Other Investments [Member] | UNITED KINGDOM
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Other Investments [Member] | IRELAND
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	0
Other Investments [Member] | Spain [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	26,900
Other Investments [Member] | Other United States [Member]
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures ($81.1 and $68.4 carried at fair value as of December 31, 2013 and 2012)	$ 7,600	$ 5,300