Investments in Unconsolidated Entities - Balance of Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments [Roll Forward]
Balance as of December 31, 2018			$ 30,565
Net income	$ 3,027	$ (579)	1,919	$ (1,617)
Distributions			(11,438)
Other comprehensive loss	(73)	$ (12)	(251)	$ 224
Balance as of September 30, 2019	20,795		20,795
Digital Realty Joint Venture
Investments [Roll Forward]
Balance as of December 31, 2018			27,291
Net income			(1,690)
Distributions			(5,000)
Other comprehensive loss			300
Balance as of September 30, 2019	20,350		20,350
Heritage Common X
Investments [Roll Forward]
Balance as of December 31, 2018			3,274
Net income			3,609
Distributions			(6,438)
Other comprehensive loss			0
Balance as of September 30, 2019	$ 445		445
Disposition and other advisory fees owed			600
Third party fees and taxes incurred			$ 1,100