Goodwill and Other Intangible Assets (Details 2) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Intangible Assets by Category
Gross Carrying Amount	$ 254,466,000		$ 254,466,000		$ 249,777,000
Accumulated Amortization	146,900,000		146,900,000		128,818,000
Amortization expense for intangible assets	7,900,000	8,200,000	15,800,000	16,600,000
Estimated amortization expense
2011			31,000,000
2012			17,000,000
2013			15,000,000
2014			13,000,000
2015			8,000,000
Customer related
Intangible Assets by Category
Gross Carrying Amount	188,452,000		188,452,000		184,864,000
Accumulated Amortization	112,046,000		112,046,000		98,104,000
Non-compete agreements
Intangible Assets by Category
Gross Carrying Amount	1,402,000		1,402,000		1,386,000
Accumulated Amortization	1,335,000		1,335,000		1,317,000
Patents
Intangible Assets by Category
Gross Carrying Amount	7,099,000		7,099,000		6,976,000
Accumulated Amortization	5,096,000		5,096,000		4,868,000
Technology related
Intangible Assets by Category
Gross Carrying Amount	30,229,000		30,229,000		29,821,000
Accumulated Amortization	13,512,000		13,512,000		11,863,000
Trade names
Intangible Assets by Category
Gross Carrying Amount	19,086,000		19,086,000		18,635,000
Accumulated Amortization	6,973,000		6,973,000		5,188,000
Other
Intangible Assets by Category
Gross Carrying Amount	8,198,000		8,198,000		8,095,000
Accumulated Amortization	$ 7,938,000		$ 7,938,000		$ 7,478,000