Unconsolidated Investments - Cash Distributions by Investment Type and Location (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Schedule of Equity Method Investments [Line Items]
Operating	$ 17.0
Investing	8.0	11.0
Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	5.5
Investing	2.0
Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	7.2
Investing	3.6
Loan Pool [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.6
Investing	2.2
Residential [Member]
Schedule of Equity Method Investments [Line Items]
Operating	2.7
Investing	0.2
Western United States
Schedule of Equity Method Investments [Line Items]
Operating	14.3
Investing	6.4
Western United States | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	5.5
Investing	2.0
Western United States | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	6.1
Investing	2.0
Western United States | Loan Pool [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0
Investing	2.2
Western United States | Residential [Member]
Schedule of Equity Method Investments [Line Items]
Operating	2.7
Investing	0.2
United Kingdom
Schedule of Equity Method Investments [Line Items]
Operating	2.7
Investing	1.6
United Kingdom | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0
Investing	0
United Kingdom | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.1
Investing	1.6
United Kingdom | Loan Pool [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.6
Investing	0
United Kingdom | Residential [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0
Investing	$ 0