Goodwill and Intangible Assets (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Intangible assets
Weighted average amortization period of intangible assets	10 years 3 months 18 days	10 years 3 months 18 days
Gross Assets	$ 271,549	$ 263,061
Accumulated Amortization	(91,393)	(61,656)
Intangible assets, net	180,156	201,405
Amortization expense	29,691	20,699	12,588
Estimated future amortization of intangible assets
2013	29,953
2014	29,021
2015	26,350
2016	20,642
2017	16,395
Thereafter	57,795
Intangible assets, net	180,156	201,405
Customer relationships
Intangible assets
Weighted average amortization period of intangible assets	11 years 1 month 6 days	11 years 2 months 12 days
Gross Assets	197,517	193,298
Accumulated Amortization	(63,436)	(45,894)
Intangible assets, net	134,081	147,404
Estimated future amortization of intangible assets
Intangible assets, net	134,081	147,404
Trade name
Intangible assets
Weighted average amortization period of intangible assets	12 years 2 months 12 days	12 years 2 months 12 days
Gross Assets	32,292	31,769
Accumulated Amortization	(12,897)	(9,835)
Intangible assets, net	19,395	21,934
Estimated future amortization of intangible assets
Intangible assets, net	19,395	21,934
Developed technology
Intangible assets
Weighted average amortization period of intangible assets	4 years 4 months 24 days	4 years 3 months 18 days
Gross Assets	21,693	19,658
Accumulated Amortization	(7,987)	(3,060)
Intangible assets, net	13,706	16,598
Estimated future amortization of intangible assets
Intangible assets, net	13,706	16,598
Noncompetition agreements
Intangible assets
Weighted average amortization period of intangible assets	4 years 8 months 12 days	4 years 9 months 18 days
Gross Assets	20,047	18,336
Accumulated Amortization	(7,073)	(2,867)
Intangible assets, net	12,974	15,469
Estimated future amortization of intangible assets
Intangible assets, net	$ 12,974	$ 15,469