Goodwill and Intangible Assets, net (Schedule of Goodwill and Other Intangible Assets) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Goodwill	$ 571,638	$ 566,427
Less - accumulated amortization	(5,425)	(5,425)
Goodwill, net	566,213	561,002	521,859	485,101
Customer lists and relationships	72,455	71,153
Non-compete agreements	21,260	20,994
Other	24,031	23,521
Intangible assets, at cost	117,746	115,668
Less - accumulated amortization	(98,213)	(92,474)
Intangible assets, net	19,533	23,194	29,851	30,352
Goodwill and intangible assets, net	585,746	584,196
Customer Lists and Relationships [Member]
Intangible assets, net	14,491
Non-compete Agreements [Member]
Intangible assets, net	1,242
Other [Member]
Intangible assets, net	$ 3,800

Finite-lived intangible assets and goodwill, net.

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Goodwill accumulated amortization prior to accounting change for amortizing good will.

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Gross carrying amount before accumulated amortization as of the balance sheet date of an asset comprised of customer information, acquired in a business combination or other transaction, having a finite beneficial life.

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The accumulated amount of amortization of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

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Sum of the gross carrying amounts before accumulated amortization as of the balance sheet date of all intangible assets having statutory or estimated useful lives. The aggregate gross carrying amount (including any previously recognized impairment charges) of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

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Gross carrying amount before accumulated amortization as of the balance sheet date of payments made to third parties in exchange for their agreement not to engage in specified competitive practices in specified geographic territories for a specified period of time.

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Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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Gross carrying amount before accumulated amortization as of the balance sheet date of intangible assets not otherwise specified in the taxonomy having a reasonably expected period of economic benefit.

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