Property Dispositions, Discontinued Operations and Real Estate Impairment - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2015 Property	Jun. 30, 2015 USD ($) Property	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Property	Jun. 30, 2014 USD ($) Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate number of properties sold | Property					6
Debt satisfaction gains (charges), net		$ 3,776	$ (4,187)	$ 14,151	$ (7,491)
Discontinued operation asset impairment charges		0	8,382	0	10,691
Impairment of real estate				1,252	16,400
Impaired real estate investment property, at cost		2,196	$ 5,574	2,196	5,574
Non-recourse debt		$ 17,234		$ 17,234
Real Estate Properties Held For Sale | Property		2		2
Mortgages [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt extinguishment amount				$ 30,293	9,900
Sold Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Aggregate gross disposition price				82,025	52,605
Gain on sale of properties				$ 23,151	$ 3,510
Transferred Property [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate number of properties transferred | Property				2	1
Debt satisfaction gains (charges), net				$ 10,466	$ (299)
Office Building [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate number of properties sold | Property				3
Subsequent Event [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate number of properties sold | Property	2