Fair-Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Interest income (expense), net	$ (2,242)	$ (3,987)	$ (10,042)	$ (13,035)
Interest Rate Swap [Member]
Derivative [Line Items]
Interest income (expense), net			3,700	(800)
Interest Rate Swap Buyouts [Member]
Derivative [Line Items]
Interest income (expense), net			$ 900	$ 300