Investments in Real Estate - Investments in Existing Properties (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Investments in real estate properties
Capitalized costs on existing portfolio	$ 10,336	$ 15,834
Investments in existing properties
Investments in real estate properties
Capitalized costs on existing portfolio	5,100	11,000
Re-leasing costs	1,000	1,900
Recurring capital expenditures	126	577
Nonrecurring building improvements	$ 4,000	$ 8,500