Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Derivative, notional amount	$ 50,000		$ 50,000
Interest income	24	$ 54	95	$ 110
Interest expense	1,654	2,181	3,612	4,289
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Fair Value, Balance Sheet Grouping, Financial Statement Captions
Derivative, notional amount	50,000		50,000
Interest income	$ (1)
Interest expense		$ 114	$ 34	$ 204