Goodwill and Other Intangible Assets (Schedule Of Components Of Other Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 74,148	$ 73,990
Accumulated Amortization	(57,247)	(53,262)
Net Carrying Amount	16,901	20,728
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	53,048	52,890
Accumulated Amortization	(46,798)	(43,617)
Net Carrying Amount	$ 6,250	$ 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	(6,256)	(5,775)
Net Carrying Amount	$ 9,144	$ 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	(4,193)	(3,870)
Net Carrying Amount	$ 107	$ 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