Basis of Presentation (Details) $ in Millions		Sep. 30, 2016 USD ($) property	Dec. 31, 2015 USD ($)
Noncontrolling Interest [Line Items]
Assets	[1]	$ 7,966.8	$ 7,595.6
Properties, Loans and Servicing Platform in Europe [Member] | Europe [Member]
Noncontrolling Interest [Line Items]
Assets		840.6
KWE [Member]
Noncontrolling Interest [Line Items]
Investments in subsidiaries		$ 486.7
Ownership percentage by parent		21.80%	18.20%
Properties, Loans and Servicing Platform in Europe [Member]
Noncontrolling Interest [Line Items]
Number of real estate investment properties in Europe | property		17
Properties, Loans and Servicing Platform in Europe [Member] | Europe [Member]
Noncontrolling Interest [Line Items]
Ownership percentage by parent		57.00%
Equity in consolidated investments		$ 417.7

[1] The assets and liabilities as of September 30, 2016 include $4,913.0 million (including cash held by consolidated investments of $647.5 million and real estate and acquired in place lease values, net of accumulated depreciation and amortization of $3,914.1 million) and $2,877.6 million (including investment debt of $2,566.7 million), respectively, from consolidated variable interest entities ("VIEs"). The assets and liabilities as of December 31, 2015 include $4,973.9 million (including cash held by consolidated investments of $507.8 million and real estate and acquired in place lease values, net of accumulated depreciation and amortization of $3,955.8 million) and $2,655.1 million (including investment debt of $2,414.0 million), respectively, from VIEs. These assets can only be used to settle obligations of the consolidated VIEs, and the liabilities do not have recourse to the Company.