Income Taxes (Schedule Of Difference Between Actual Income Tax Provision For Continuing Operations And Income Tax Provision Calculated At Statutory U.S. Federal Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Abstract]
Income tax provision calculated using the statutory rate of 21%	$ 54,938	$ 50,316	$ 40,921
Stock compensation tax benefits	(24,177)	(22,862)	(18,932)
State and local income taxes, less federal income tax effect	7,880	7,150	4,600
Nondeductible expenses	3,048	2,280	1,041
Enactment of the tax reform act			(8,305)
Other --net	(3)	(2,828)	(585)
Income tax provision	$ 41,686	$ 34,056	$ 18,740
Effective tax rate	15.90%	14.20%	16.00%