Income Taxes (Schedule Of Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits ) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Beginning of year	$ 3,408,000	$ 5,375,000	$ 8,288,000
Additions based on tax positions related to the current year	941,000	756,000	1,765,000
Additions for tax positions in prior years	289,000	487,000	428,000
Reductions for tax positions in prior years	(63,000)	(2,949,000)	(336,000)
Reductions as a result of completed audit examinations	0	0	(4,162,000)
Reductions as a result of a lapse of the applicable statute of limitations	(140,000)	(261,000)	(608,000)
End of year	$ 4,435,000	$ 3,408,000	$ 5,375,000