Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - Unrealized Gain On Available-For-Sale Marketable Securities [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income balance, beginning balance	$ 5,880
Amount reclassified to retained earnings for equity unrealized gain (adoption of ASU 2016-01)	(5,482)
Other comprehensive loss before reclassifications	(445)
Amounts reclassified from accumulated other comprehensive income	39
Net current period change in other comprehensive income	(5,888)
Accumulated other comprehensive income balance, ending balance	$ (8)