Goodwill and Other Intangible Assets (Schedule Of Components Of Other Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 73,530	$ 73,530
Accumulated Amortization	(51,919)	(47,905)
Total	21,611	25,625
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	52,430	52,430
Accumulated Amortization	(42,542)	(39,332)
Total	$ 9,888	$ 13,098
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	(5,615)	(5,133)
Total	$ 9,785	$ 10,267
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	(3,762)	(3,440)
Total	$ 538	$ 860
Useful Lives (in years)	10 years	10 years
Licensing Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,400	$ 1,400
Total	$ 1,400	$ 1,400