Unconsolidated Investments - Cash Distributions by Investment Type and Location (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]
Operating	$ 50.8
Investing	92.0	$ 99.3
Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	22.8
Investing	5.2
Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	11.2
Investing	33.8
Loan Pools [Member]
Schedule of Equity Method Investments [Line Items]
Operating	8.2
Investing	50.0
Residential and Other [Member]
Schedule of Equity Method Investments [Line Items]
Operating	8.6
Investing	3.0
Western United States [Member]
Schedule of Equity Method Investments [Line Items]
Operating	40.2
Investing	42.5
Western United States [Member] | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	22.7
Investing	5.2
Western United States [Member] | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	10.0
Investing	$ 32.0
Western United States [Member] | Loan Pools [Member]
Schedule of Equity Method Investments [Line Items]
Operating
Investing	$ 2.3
Western United States [Member] | Residential and Other [Member]
Schedule of Equity Method Investments [Line Items]
Operating	7.5
Investing	3.0
Japan [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.1
Investing	0.0
Japan [Member] | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.1
Investing	0.0
Japan [Member] | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	$ 0.0
Japan [Member] | Loan Pools [Member]
Schedule of Equity Method Investments [Line Items]
Operating
Investing
Japan [Member] | Residential and Other [Member]
Schedule of Equity Method Investments [Line Items]
Operating	$ 0.0
Investing	0.0
United Kingdom [Member]
Schedule of Equity Method Investments [Line Items]
Operating	7.6
Investing	43.3
United Kingdom [Member] | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	0.0
United Kingdom [Member] | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.2
Investing	1.8
United Kingdom [Member] | Loan Pools [Member]
Schedule of Equity Method Investments [Line Items]
Operating	6.4
Investing	41.5
United Kingdom [Member] | Residential and Other [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	0.0
Ireland [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.8
Investing	6.2
Ireland [Member] | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	0.0
Ireland [Member] | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	0.0
Ireland [Member] | Loan Pools [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.8
Investing	6.2
Ireland [Member] | Residential and Other [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	0.0
Spain [Member]
Schedule of Equity Method Investments [Line Items]
Operating	1.1
Investing	0.0
Spain [Member] | Multifamily [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	0.0
Spain [Member] | Commercial [Member]
Schedule of Equity Method Investments [Line Items]
Operating	0.0
Investing	$ 0.0
Spain [Member] | Loan Pools [Member]
Schedule of Equity Method Investments [Line Items]
Operating
Investing
Spain [Member] | Residential and Other [Member]
Schedule of Equity Method Investments [Line Items]
Operating	$ 1.1
Investing