Supplementary Balance Sheet Detail (Schedule Of Analysis Of The Allowance For Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 1,129	$ 1,097	$ 326
Additions	4,636	122	771
Deductions	291	90	0
Balance at end of year	$ 5,474	$ 1,129	$ 1,097