Goodwill and Intangible Assets, net (Schedule of Intangible Assets Estimated Useful Lives) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Intangible assets remaining amortization, Weighted Average Remaining Years	3.9
Intangible assets remaining amortization, Amount	$ 19,533	$ 23,194	$ 29,851	$ 30,352
Customer Lists and Relationships [Member]
Intangible assets remaining amortization, Weighted Average Remaining Years	4.0
Intangible assets remaining amortization, Amount	14,491
Non-compete Agreements [Member]
Intangible assets remaining amortization, Weighted Average Remaining Years	3.4
Intangible assets remaining amortization, Amount	1,242
Other [Member]
Intangible assets remaining amortization, Weighted Average Remaining Years	3.7
Intangible assets remaining amortization, Amount	$ 3,800