Acquisitions (Details Textual) (Maverick [Member], USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Acquisitions (Textual) [Abstract]
Revenue included in the consolidated statement of operations	$ 68,100,000
Aggregate purchase price	186,300,000
Additional depreciation		6,300,000
Amortization expense, for the amortization of intangible assets		1,200,000
Interest expense		6,500,000
Customer Relationships [Member]
Acquisitions (Textual) [Abstract]
Other intangible assets, amortizable	25,300,000
Other intangible assets, amortization period, years	15 years
Non-Compete Agreements [Member]
Acquisitions (Textual) [Abstract]
Other intangible assets, amortizable	3,600,000
Other intangible assets, amortization period, years	5 years
Trade Name [Member]
Acquisitions (Textual) [Abstract]
Other intangible assets, indefinite life	170,000
Intellectual Property [Member]
Acquisitions (Textual) [Abstract]
Other intangible assets, amortizable	$ 380,000
Other intangible assets, amortization period, years	15 years