Accumulated Other Comprehensive Income (Schedule Of Reclassifications out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment income and interest expense	$ (532)	$ 824
Provision for income taxes	(6,116)	(9,238)
Net income	16,191	$ 11,836
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment income and interest expense	54
Provision for income taxes	(15)
Net income	$ 39