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
Derivative [Line Items]
Interest expense (income)	$ (4,621)	$ (4,285)	$ (8,909)	$ (8,613)
Interest Rate Current Swap [Member]
Derivative [Line Items]
Interest expense (income)			700	500
Interest Rate Swap Buyouts [Member]
Derivative [Line Items]
Interest expense (income)			$ (400)	$ 400