Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Intangible Assets, by category
Gross Carrying Amount		$ 207,974		$ 207,974		$ 206,429
Accumulated Amortization		149,941		149,941		147,905
Amortization expense for intangible assets		2,179	$ 2,593	4,316	$ 5,146
Estimated amortization expense for next 5 years
2015	[1]	8,750		8,750
2016	[1]	8,250		8,250
2017	[1]	5,500		5,500
2018	[1]	5,250		5,250
2019	[1]	5,250		5,250
Customer related
Intangible Assets, by category
Gross Carrying Amount		157,864		157,864		157,530
Accumulated Amortization		112,747		112,747		112,211
Non-compete agreements
Intangible Assets, by category
Gross Carrying Amount		1,097		1,097		1,107
Accumulated Amortization		1,043		1,043		1,039
Patents
Intangible Assets, by category
Gross Carrying Amount		6,957		6,957		6,079
Accumulated Amortization		5,533		5,533		5,399
Technology related
Intangible Assets, by category
Gross Carrying Amount		26,142		26,142		26,548
Accumulated Amortization		22,261		22,261		21,233
Trade names
Intangible Assets, by category
Gross Carrying Amount		8,317		8,317		7,745
Accumulated Amortization		3,963		3,963		3,733
Other
Intangible Assets, by category
Gross Carrying Amount		7,597		7,597		7,420
Accumulated Amortization		$ 4,394		$ 4,394		$ 4,290

[1] These estimated amortization expense amounts do not reflect the potential effect of future foreign currency exchange fluctuations.