Marketable Securities (Schedule Of Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value
In Unrealized Loss Position For Less Than 12 Months	$ 15,716	$ 741
In Unrealized Loss Position For Greater Than 12 Months	355	0
Gross Unrealized Losses
In Unrealized Loss Position For Less Than 12 Months	(86)	(1)
In Unrealized Loss Position For Greater Than 12 Months	(2)	0
U.S. Government And Agency Obligations [Member]
Fair Value
In Unrealized Loss Position For Less Than 12 Months	9,250	330
In Unrealized Loss Position For Greater Than 12 Months	0	0
Gross Unrealized Losses
In Unrealized Loss Position For Less Than 12 Months	(57)	0
In Unrealized Loss Position For Greater Than 12 Months	0	0
Corporate Debt Securities And Certificates Of Deposit [Member]
Fair Value
In Unrealized Loss Position For Less Than 12 Months	5,188	411
In Unrealized Loss Position For Greater Than 12 Months	355	0
Gross Unrealized Losses
In Unrealized Loss Position For Less Than 12 Months	(18)	(1)
In Unrealized Loss Position For Greater Than 12 Months	(2)	$ 0
Asset Backed Securities [Member]
Fair Value
In Unrealized Loss Position For Less Than 12 Months	1,278
In Unrealized Loss Position For Greater Than 12 Months	0
Gross Unrealized Losses
In Unrealized Loss Position For Less Than 12 Months	(11)
In Unrealized Loss Position For Greater Than 12 Months	$ 0