SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Analysis of Carrying Amount of Real Estate Properties and Accumulated Depreciation (Footnote) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Aggregate cost of properties for federal income tax purposes	$ 1,907,759,000
Real estate properties additions due to changes in foreign currency exchange	0	$ 0	$ (13,217,000)
Accumulated depreciation additions due to changes in foreign currency exchange	$ 0	$ 0	$ (887,000)
Maximum | Buildings and improvements
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful lives	40 years
Maximum | Personal property
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful lives	12 years