Fair-Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Interest expense		$ 19,650	$ 20,242	$ 18,602
Interest Rate Swap [Member]
Derivative [Line Items]
Interest expense			500	800
Interest income		600
Interest Rate Swap Buyouts [Member]
Derivative [Line Items]
Interest income		$ 500	$ 600	$ 700
Interest Rate Swap Buyouts [Member] | Subsequent Event [Member]
Derivative [Line Items]
Interest income	$ 1,300