Goodwill and Other Intangible Assets (Schedule Of Components Of Other Intangible Assets) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 74,135	$ 73,990
Accumulated Amortization	(55,879)	(53,262)
Net Carrying Amount	18,256	20,728
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	53,035	52,890
Accumulated Amortization	(45,698)	(43,617)
Net Carrying Amount	$ 7,337	$ 9,273
Useful Lives (in years)	11 years	11 years
Trade names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 15,400	$ 15,400
Accumulated Amortization	(6,096)	(5,775)
Net Carrying Amount	$ 9,304	$ 9,625
Useful Lives (in years)	24 years	24 years
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,300	$ 4,300
Accumulated Amortization	(4,085)	(3,870)
Net Carrying Amount	$ 215	$ 430
Useful Lives (in years)	10 years	10 years
Licensing Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,400	$ 1,400
Net Carrying Amount	$ 1,400	$ 1,400