Fair-Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative [Line Items]
Interest income (expense), net	$ (4,218)	$ (3,823)	$ (7,787)	$ (7,800)
Interest Rate Swap
Derivative [Line Items]
Interest income (expense), net			3,500	1,900
Interest Rate Swap Buyouts
Derivative [Line Items]
Interest income (expense), net			$ 300	$ 400