Fair-Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Interest expense	$ 4,784	$ 4,356	$ 13,843	$ 10,957
Interest Rate Current Swap [Member]
Derivative [Line Items]
Interest expense			600	1,200
Interest Rate Swap Buyouts [Member]
Derivative [Line Items]
Interest expense			$ 600	$ 500