Real Estate Properties - Summary of Properties Sold (Footnote) (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jun. 30, 2014	Jan. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Real Estate Properties [Line Items]
Mortgage financing related to property sold					$ 7,688
Loss on asset impairment from discontinued operations			$ 0	$ (2,238)	(102,869)
Loss on early extinguishment of debt from discontinued operations			$ 0	$ (3,345)	$ (1,011)
Disposed of by Sale | Sales of properties resulting in gains and losses
Real Estate Properties [Line Items]
Mortgage financing related to property sold		$ 7,700
Interest rate on real estate mortgage receivable		6.00%
Disposed of by Sale | Sales of properties with previously recorded asset impairment losses:
Real Estate Properties [Line Items]
Loss on asset impairment from discontinued operations	$ 2,200
Loss on early extinguishment of debt from discontinued operations	$ 3,300