Goodwill And Other Intangible Assets (Schedule Of Intangible Assets By Major Class) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Goodwill And Other Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	$ 194,824	$ 192,846
Finite lived intangible assets, Accumulated Amortization	85,758	79,557
Intangible assets, Gross Carrying Amount	200,424	198,446
Intangible assets, Accumulated Amortization	85,758	79,557
Tradenames [Member]
Goodwill And Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, Gross Carrying Amount	5,600	5,600
Indefinite-lived intangible assets, Useful Life	Indefinite
Customer Relationships [Member]
Goodwill And Other Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	146,605	144,696
Finite lived intangible assets, Accumulated Amortization	53,437	49,381
Finite lived intangible assets, Useful Life in Years, Minimum	1
Finite lived intangible assets, Useful Life in Years, Maximum	15
Non-Competition Agreements [Member]
Goodwill And Other Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	14,670	14,601
Finite lived intangible assets, Accumulated Amortization	9,565	8,965
Finite lived intangible assets, Useful Life in Years, Minimum	1
Finite lived intangible assets, Useful Life in Years, Maximum	10
Software [Member]
Goodwill And Other Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	33,549	33,549
Finite lived intangible assets, Accumulated Amortization	$ 22,756	$ 21,211
Finite lived intangible assets, Useful Life in Years, Minimum	3
Finite lived intangible assets, Useful Life in Years, Maximum	6