Goodwill and Other Intangible Assets (Schedule Of Components Of Other Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 74,312	$ 74,148
Accumulated Amortization	(59,875)	(58,614)
Net Carrying Amount	14,437	15,534
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	53,212	53,048
Accumulated Amortization	(48,998)	(47,897)
Net Carrying Amount	$ 4,214	$ 5,151
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	(6,577)	(6,417)
Net Carrying Amount	$ 8,823	$ 8,983
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	(4,300)	(4,300)
Net Carrying Amount	$ 0	$ 0
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