Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt, net of deferred financing costs	$ 115,605	$ 47,918
Fixed rate debt	24,317	30,159
Variable rate debt	99,768	33,230
Tangible net worth	$ 55,000
Percentage of net offering proceeds added to tangible net worth	80.00%
Western Alliance Bank [Member]
Debt Instrument [Line Items]
Maturity date of debt	Feb. 28, 2017
Fixed rate debt		4,806
KeyBank Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date of debt	Mar. 31, 2020
Weighted average interest rate	4.55%
Variable rate debt	$ 73,303
Held For Use [Member]
Debt Instrument [Line Items]
Long-term debt, net of deferred financing costs	$ 118,935	$ 48,419
Weighted average term	3 years 2 months 12 days	3 years 2 months 12 days
Weighted average interest rate	4.50%	4.94%
Fixed rate debt	$ 24,317	$ 22,550
Fixed rate, weighted average term	2 years 4 months 24 days	3 years 8 months 12 days
Fixed rate, weighted average interest	4.41%	4.41%
Variable rate debt	$ 94,618	$ 25,869
Variable rate, weighted average term	4 years 1 month 6 days	2 years 9 months 18 days
Variable rate, weighted average interest	4.52%	5.39%
Minimum [Member]
Debt Instrument [Line Items]
Fixed charge coverage ratio	1.50
Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	60.00%
Leverage ratio after extension option	6.25
Secured leverage ratio	40.00%
Unhedged variable rate debt	25.00%
Distributions, percentage of funds available aloowed	95.00%