Reportable Segments (Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information
Total revenues	$ 33,083	$ 25,508	$ 23,554	$ 21,738	$ 20,486	$ 15,878	$ 15,974	$ 16,731	$ 103,883	$ 69,069	$ 59,724
Domestic office investments
Segment Reporting Information
Total revenues									16,538	16,398	15,437
Domestic residential/living investments
Segment Reporting Information
Total revenues									12,050	6,637	4,671
Domestic retail investments
Segment Reporting Information
Total revenues									23,142	20,235	19,507
Domestic industrial investments
Segment Reporting Information
Total revenues									4,408	5,698	7,619
International industrial investments
Segment Reporting Information
Total revenues									28,997	3,630	0
International office investments
Segment Reporting Information
Total revenues									8,931	7,731	8,711
International residential/living investments
Segment Reporting Information
Total revenues									$ 9,817	$ 8,740	$ 3,779