Income Taxes (Schedule Of Components Of Provision (Benefit) For Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Provision Benefit For Income Taxes [Line Items]
Provision (benefit) for deferred income taxes	$ (7,918)	$ 20,881	$ 5,143
Provision for income taxes	117,788	99,792	81,006
Current [Member]
Provision Benefit For Income Taxes [Line Items]
Federal	92,453	53,285	52,966
State	9,258	6,608	5,353
International	23,993	19,291	17,681
Provision for current income taxes	125,704	79,184	76,000
Deferred [Member]
Provision Benefit For Income Taxes [Line Items]
Federal	(1,201)	20,305	5,762
State	(4,102)	1,196	526
International	(2,613)	(893)	(1,282)
Provision (benefit) for deferred income taxes	$ (7,916)	$ 20,608	$ 5,006