Summary Of Significant Accounting Policies (Composition Of Intangible And Other Long-term Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of Intangible Assets by Major Class [Line Items]
Gross Amount	$ 32,273	$ 158,565
Accumulated Amortization	(23,199)	(76,358)
Net Balance	$ 9,074	82,207
Customer Relationships [Member]
Schedule of Intangible Assets by Major Class [Line Items]
Estimated Useful Lives	17 years
Gross Amount	$ 19,902	133,374
Accumulated Amortization	(14,680)	(59,711)
Net Balance	$ 5,222	73,663
Tradenames [Member]
Schedule of Intangible Assets by Major Class [Line Items]
Estimated Useful Lives	10 years
Gross Amount	$ 8,907	20,717
Accumulated Amortization	(5,413)	(13,334)
Net Balance	$ 3,494	7,383
Non-compete [Member]
Schedule of Intangible Assets by Major Class [Line Items]
Estimated Useful Lives	3 years
Gross Amount	$ 3,464	4,474
Accumulated Amortization	(3,106)	(3,313)
Net Balance	$ 358	$ 1,161