Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Intangible Assets, by category
Gross Carrying Amount	$ 201,527		$ 201,527		$ 195,074
Accumulated Amortization	162,187		162,187		153,507
Amortization expense for intangible assets	1,269	$ 2,053	3,868	$ 6,208
Estimated amortization expense for next 5 years
2017	5,000		5,000
2018	4,750		4,750
2019	4,500		4,500
2020	4,250		4,250
2021	4,000		4,000
Customer related
Intangible Assets, by category
Gross Carrying Amount	152,423		152,423		146,840
Accumulated Amortization	119,870		119,870		112,610
Patents
Intangible Assets, by category
Gross Carrying Amount	5,832		5,832		5,729
Accumulated Amortization	5,697		5,697		5,534
Technology related
Intangible Assets, by category
Gross Carrying Amount	26,151		26,151		25,687
Accumulated Amortization	26,151		26,151		25,634
Trade names
Intangible Assets, by category
Gross Carrying Amount	8,316		8,316		8,306
Accumulated Amortization	4,767		4,767		4,529
Other
Intangible Assets, by category
Gross Carrying Amount	8,805		8,805		8,512
Accumulated Amortization	$ 5,702		$ 5,702		$ 5,200