Long-Term Debt (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Debt Instrument [Line Items]
Debt to be repaid upon sale of related properties, term	1 year
Minimum [Member]
Debt Instrument [Line Items]
Fixed charge coverage ratio	1.50
Tangible net worth	$ 55.0
Percentage of net offering proceeds added to tangible net worth	80.00%
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%