Intangible Assets (Narrative) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Finite-Lived Intangible Assets, Amortization Method			Intangible assets consist of intellectual property, non-compete agreements, customer lists and trademarks. Intellectual property, non-compete agreements and trademarks are amortized on a straight-line basis over their estimated useful lives or contract periods, generally ranging from 3 to 20 years. Customer lists are amortized based on the attrition rate of our customers.
Finite-Lived Intangible Asset, Useful Life			7 years 7 months 6 days		7 years 4 months 24 days
Amortization of Intangible Assets	$ 5,838	$ 3,583	$ 11,216	$ 7,114
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life			3 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life			20 years