Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($) Segment lease	Sep. 20, 2019 USD ($)	Mar. 31, 2019 USD ($)	Mar. 01, 2019 USD ($)	Jan. 01, 2019 USD ($) lease	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Cash equivalents or restrictions on cash	$ 0					$ 0
FDIC insured limit	$ 250,000
Number of reportable segments | Segment	1
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of ground leases | lease	3				2
Right of use asset	$ 41,347,000	$ 16,300,000	$ 600,000
Lease liability	$ 45,020,000	16,300,000		$ 600,000
Discount rate (percent)					5.36%
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right of use asset					$ 25,500,000
Lease liability					$ 27,600,000
Chicago Illinois Office
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right of use asset				$ 600,000
Discount rate (percent)				3.94%
McKesson II
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right of use asset		$ 16,300,000
Discount rate (percent)		4.36%