Indebtedness Acquisition Credit Facility (Details)	9 Months Ended
	Sep. 30, 2020 USD ($) number_of_properties	Mar. 01, 2021 USD ($)	Mar. 25, 2019 USD ($)	Mar. 23, 2018 USD ($)	Feb. 28, 2017 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 200,000,000
Unamortized Debt Issuance Expense	$ 800,000
Line Of Credit, Number Of Extension Options | number_of_properties	2
Line Of Credit, Extension Term	1 year
February 2017 facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 90,000,000		$ 200,000,000
Subsequent Event [Member] | February 2017 facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 300,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Indebtedness Weighted Average Remaining Maturity	1 year 3 months 18 days
acquisition facility [Member]
Line of Credit Facility [Line Items]
Unamortized Debt Issuance Expense	$ 100,000
Indebtedness Weighted Average Remaining Maturity	1 year 4 months 24 days
Minimum [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Loans Receivable, Basis Spread on Variable Rate	2.75%
Minimum [Member] | Revolving Credit Facility [Member] | February 2017 facility [Member]
Line of Credit Facility [Line Items]
Loans Receivable, Basis Spread on Variable Rate	1.75%
Maximum [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Loans Receivable, Basis Spread on Variable Rate	3.50%
Maximum [Member] | Revolving Credit Facility [Member] | February 2017 facility [Member]
Line of Credit Facility [Line Items]
Loans Receivable, Basis Spread on Variable Rate	2.20%