Fair-Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Interest expense (income)	$ (4,621)	$ (4,429)	$ (13,530)	$ (13,042)
Interest Rate Current Swap [Member]
Derivative [Line Items]
Interest expense (income)			600	600
Interest Rate Swap Buyouts [Member]
Derivative [Line Items]
Interest expense (income)			$ (500)	$ 600