Investment in Real Estate Fair Value Measurement on Non-Recurring Basis (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Impairment	$ (2,756)
Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Operating Property Not Held for Sale	6,416
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Operating Property Not Held for Sale	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Operating Property Not Held for Sale	0
Fair Value, Measurements, Nonrecurring | Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Operating Property Not Held for Sale	$ 6,416