Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 202,162	$ 195,074
Accumulated Amortization	163,911	153,507
Intangible assets, net	38,251	41,567
Amortization expense for intangible assets	5,100	7,900	$ 8,800
Finite-Lived Intangible Assets Including Current, Net		41,600
Estimated amortization expense for the next five years
2018	5,000
2019	4,750
2020	4,500
2021	4,250
2022	4,000
Customer related
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	153,014	146,840
Accumulated Amortization	121,385	112,610
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,825	5,729
Accumulated Amortization	5,700	5,534
Technology related
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	26,131	25,687
Accumulated Amortization	26,131	25,634
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,317	8,306
Accumulated Amortization	4,845	4,529
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,875	8,512
Accumulated Amortization	$ 5,850	$ 5,200