Fair-Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Interest income (expense), net	$ (3,823)	$ (4,631)	$ (7,800)	$ (9,048)
Interest Rate Swap [Member]
Derivative [Line Items]
Interest income (expense), net	1,900	(600)
Interest Rate Swap Buyouts [Member]
Derivative [Line Items]
Interest income (expense), net	$ 400	$ 200