Goodwill and Other Intangible Assets Finite life intangibles Gross and Net at balance sheet dates (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Mar. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 90,477	$ 90,525
Finite-Lived Intangible Assets, Accumulated Amortization	4,927	5,996
Finite-Lived Intangible Assets, Net	85,550	84,529
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	54,730	54,730
Finite-Lived Intangible Assets, Accumulated Amortization	3,081	3,620
Finite-Lived Intangible Assets, Net	51,649	51,110
acquired technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	27,580	27,580
Finite-Lived Intangible Assets, Accumulated Amortization	1,128	1,495
Finite-Lived Intangible Assets, Net	26,452	26,085
Patents [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	1,217	1,265
Finite-Lived Intangible Assets, Accumulated Amortization	259	268
Finite-Lived Intangible Assets, Net	958	997
Finite-Lived Intangible Asset, Useful Life	20 years
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	6,890	6,890
Finite-Lived Intangible Assets, Accumulated Amortization	414	563
Finite-Lived Intangible Assets, Net	6,476	6,327
Noncompete Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	60	60
Finite-Lived Intangible Assets, Accumulated Amortization	45	50
Finite-Lived Intangible Assets, Net	$ 15	$ 10
Finite-Lived Intangible Asset, Useful Life	3 years
Minimum [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Minimum [Member] | acquired technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Minimum [Member] | Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	30 years
Maximum [Member] | acquired technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	20 years
Maximum [Member] | Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	12 years