Goodwill and Other Intangible Assets (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Intangible Assets, by category
Gross Carrying Amount	$ 252,483		$ 252,483		$ 250,597
Accumulated Amortization	170,826		170,826		157,096
Amortization expense for intangible assets	4,111	7,898	13,518	23,690
Estimated amortization expense for next 5 years
2012	17,500		17,500
2013	15,750		15,750
2014	13,500		13,500
2015	8,750		8,750
2016	7,500		7,500
Customer related
Intangible Assets, by category
Gross Carrying Amount	185,128		185,128		183,576
Accumulated Amortization	128,844		128,844		119,708
Non-compete agreements
Intangible Assets, by category
Gross Carrying Amount	1,347		1,347		1,353
Accumulated Amortization	1,307		1,307		1,301
Patents
Intangible Assets, by category
Gross Carrying Amount	6,899		6,899		6,884
Accumulated Amortization	5,419		5,419		5,145
Technology related
Intangible Assets, by category
Gross Carrying Amount	29,609		29,609		29,497
Accumulated Amortization	16,808		16,808		14,614
Trade names
Intangible Assets, by category
Gross Carrying Amount	18,654		18,654		18,538
Accumulated Amortization	10,871		10,871		8,379
Other
Intangible Assets, by category
Gross Carrying Amount	10,846		10,846		10,749
Accumulated Amortization	$ 7,577		$ 7,577		$ 7,949