Real Estate and In-Place Lease Value Real Estate and In-Place Lease Value - Schedule of Acquisitions (Details) (USD $) In Millions, unless otherwise specified		3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014 Commercial Acquired in United Kingdom 1 [Member] Property		Mar. 31, 2014 Hotel Acquired in Western United States [Member] room	Mar. 31, 2014 Multifamily Acquired in Ireland [Member] penthouse_unit sqft apartment_unit Property	Mar. 31, 2014 Commercial Acquired in United Kingdom 2 [Member] Property		Mar. 31, 2014 Multifamily Acquired in Ireland 2 [Member] apartment_unit sqft acre		Feb. 28, 2014 KWE [Member]
Business Acquisition [Line Items]
Land	$ 118.3	$ 29.7	[1]	$ 1.3	$ 0.6	$ 54.0	[2]	$ 32.7	[3]
Building	283.8	47.5	[1]	8.3	15.1	132.0	[2]	80.9	[3]
Intangible assets	95.8	40.2	[1]	0	0.4	54.0	[2]	1.2	[3]
Mortgage loans	$ 88.5	$ 0	[1]	$ 0	$ 9.6	$ 0	[2]	$ 78.9	[3]
Number of properties acquired		14			3	26
Number of rooms acquired				193
Number of apartment units acquired					24			281
Number of penthouse units acquired					2
Square feet of property acquired					1,000			725
Number of acres acquired								7.4
Contribution of interest percentage in portfolio										50.00%

[1] On February 28, 2014, the Company contributed its 50% interest in this portfolio to KWE as part of the Company's investment in KWE's initial public offering.

[2] This portfolio of properties was acquired by KWE.

[3] Company entered into a purchase agreement with KWE subsequent to March 31, 2014. See Note 17.