Fair Value Measurements and Derivative Instruments (Schedule of Carrying Value and Estimated Fair Value of Long-Term Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt	$ 134,029	$ 136,930
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt	134,197	135,893
Held For Use [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt	134,029	135,810
Held For Use [Member] | Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt	$ 134,197	134,773
Held For Sale [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt		1,120
Held For Sale [Member] | Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of debt		$ 1,120