Goodwill and Intangible Assets Intangibles (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 132,132	$ 132,703
Accumulated Amortization	53,030	50,226
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years 9 months 18 days
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	118,589	119,118
Accumulated Amortization	47,726	45,317
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years 3 months 18 days
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,888	3,888
Accumulated Amortization	3,319	3,235
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years
Trade name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,255	8,297
Accumulated Amortization	1,382	1,188
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	9 years 4 months 24 days
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,400	1,400
Accumulated Amortization	$ 603	$ 486
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years