Receivables (Schedule of Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 1,062	$ 7,393	$ 8,468
Charged to costs and expenses, net of recoveries	5,504	(5,572)	31
Amounts written off	(308)	(759)	(1,106)
Balance at end of period	$ 6,258	$ 1,062	$ 7,393