Summary of Significant Accounting Policies - Expense Recoveries (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accounting Policies [Abstract]
Provision for bad debts			$ (512,000)	$ (2,158,000)
Property, Plant and Equipment [Line Items]
Provision for bad debts			512,000	2,158,000
Absolute Net Leases
Accounting Policies [Abstract]
Provision for bad debts	$ 100,000	$ 0	100,000	100,000
Property, Plant and Equipment [Line Items]
Provision for bad debts	$ (100,000)	$ 0	$ (100,000)	$ (100,000)