Significant Accounting Policies (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) derivative segment	Mar. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($) derivative
Significant Accounting Policies Statement [Line Items]
Property impairment charges	$ 0	$ 0
Amortization of above and below-market leases	$ 900,000	900,000
Remaining weighted average lease term related to these intangible assets and liabilities	8 years 10 months 12 days
Straight-line rent and accounts receivables, net of allowances	$ 33,900,000			$ 25,700,000
Straight-line rent and accounts receivable, allowances	200,000			200,000
Deferred financing cost accumulated amortization	$ 7,200,000			6,900,000
Performance measurment period	3 years
Interest rate cap notional value	$ 150,000,000
Interest rate cap fair value	2,000			$ 26,000
Lease liability	800,000		$ 900,000
Right-of-use asset	800,000		$ 800,000
Weighted average remaining lease term			3 years 6 months 12 days
Incremental borrowing rate			2.70%
Interest rate cap [Member]
Significant Accounting Policies Statement [Line Items]
Term loan notional amount associated with interest rate cap derivative	150,000,000
Interest rate cap notional value	$ 150,000,000
Derivative cap interest rate	4.00%
Interest rate cap [Member] | Minimum [Member]
Significant Accounting Policies Statement [Line Items]
Derivative, basis spread on variable rate	1.20%
Interest rate cap [Member] | Maximum [Member]
Significant Accounting Policies Statement [Line Items]
Derivative, basis spread on variable rate	1.70%
Interest rate cap, Maturity 5/4/2021 [Member]
Significant Accounting Policies Statement [Line Items]
Term loan notional amount associated with interest rate cap derivative	$ 50,000,000
Derivative cap interest rate	4.00%
Interest rate cap, Maturity 4/1/2019 [Member]
Significant Accounting Policies Statement [Line Items]
Term loan notional amount associated with interest rate cap derivative	$ 50,000,000
Derivative cap interest rate	4.00%
Interest rate cap, Maturity 2/3/2020 [Member]
Significant Accounting Policies Statement [Line Items]
Term loan notional amount associated with interest rate cap derivative	$ 50,000,000
Derivative cap interest rate	4.00%
Real estate investment [Member]
Significant Accounting Policies Statement [Line Items]
Number of reportable segments | segment	1
Senior Secured Loan Receivable [Member]
Significant Accounting Policies Statement [Line Items]
Impairment charges	$ 0	$ 0
Cash flow hedging [Member] | Interest rate cap [Member]
Significant Accounting Policies Statement [Line Items]
Number of interest rate cap transactions | derivative	3			3