Significant Accounting Policies (Schedule of Allowance for Doubtful Accounts) (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 year	$ 8,762	$ 8,423	$ 10,258
Additions charged to expense	457	1,308	1,824
Other	(4,827)	(969)	(3,659)
Balance at end of year	$ 4,392	$ 8,762	$ 8,423