Summary Of Significant Accounting Policies (Composition Of Intangible And Other Long-term Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Intangible Assets by Major Class [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 197,912	$ 296,725
Finite-Lived Intangible Assets, Accumulated Amortization	(69,588)	(83,520)
Finite-Lived Intangible Assets, Net, Total	128,324	213,205
Customer Relationships [Member]
Schedule of Intangible Assets by Major Class [Line Items]
Acquired Finite-lived Intangible Asset, Amount	164,603	257,364
Finite-Lived Intangible Assets, Accumulated Amortization	(52,747)	(65,209)
Finite-Lived Intangible Assets, Net, Total	111,856	192,155
Trade Names [Member]
Schedule of Intangible Assets by Major Class [Line Items]
Acquired Finite-lived Intangible Asset, Amount	30,519	36,119
Finite-Lived Intangible Assets, Accumulated Amortization	(14,123)	(15,371)
Finite-Lived Intangible Assets, Net, Total	16,396	20,748
Noncompete Agreements [Member]
Schedule of Intangible Assets by Major Class [Line Items]
Acquired Finite-lived Intangible Asset, Amount	2,790	3,242
Finite-Lived Intangible Assets, Accumulated Amortization	(2,718)	(2,940)
Finite-Lived Intangible Assets, Net, Total	$ 72	$ 302