Goodwill and Other Intangible Assets (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Intangible Assets, by category
Gross Carrying Amount	$ 215,751			$ 215,751			$ 196,695
Accumulated Amortization	149,315			149,315			143,434
Amortization expense for intangible assets	2,593		3,904	5,146		7,852
Estimated amortization expense for next 5 years
2014	10,000	[1]		10,000	[1]
2015	8,750	[1]		8,750	[1]
2016	8,250	[1]		8,250	[1]
2017	5,250	[1]		5,250	[1]
2018	5,000	[1]		5,000	[1]
Customer related
Intangible Assets, by category
Gross Carrying Amount	165,842			165,842			150,307
Accumulated Amortization	114,799			114,799			110,889
Non-compete agreements
Intangible Assets, by category
Gross Carrying Amount	1,125			1,125			1,126
Accumulated Amortization	1,040			1,040			1,024
Patents
Intangible Assets, by category
Gross Carrying Amount	6,285			6,285			6,211
Accumulated Amortization	5,441			5,441			5,273
Technology related
Intangible Assets, by category
Gross Carrying Amount	27,151			27,151			27,185
Accumulated Amortization	20,311			20,311			18,931
Trade names
Intangible Assets, by category
Gross Carrying Amount	7,759			7,759			4,113
Accumulated Amortization	3,356			3,356			2,969
Other
Intangible Assets, by category
Gross Carrying Amount	7,589			7,589			7,753
Accumulated Amortization	$ 4,368			$ 4,368			$ 4,348

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