Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Intangible Assets, by category
Gross Carrying Amount	$ 250,004		$ 250,004		$ 202,162
Accumulated Amortization	163,739		163,739		163,911
Amortization expense for intangible assets	1,649	$ 1,280	2,931	$ 2,598
Estimated amortization expense for next 5 years
2018	7,900		7,900
2019	9,750		9,750
2020	9,250		9,250
2021	8,800		8,800
2022	8,500		8,500
Customer related
Intangible Assets, by category
Gross Carrying Amount	161,149		161,149		153,014
Accumulated Amortization	120,898		120,898		121,385
Patents
Intangible Assets, by category
Gross Carrying Amount	5,748		5,748		5,825
Accumulated Amortization	5,645		5,645		5,700
Technology related
Intangible Assets, by category
Gross Carrying Amount	61,646		61,646		26,131
Accumulated Amortization	26,126		26,126		26,131
Trade names
Intangible Assets, by category
Gross Carrying Amount	12,713		12,713		8,317
Accumulated Amortization	5,016		5,016		4,845
Other
Intangible Assets, by category
Gross Carrying Amount	8,748		8,748		8,875
Accumulated Amortization	$ 6,054		$ 6,054		$ 5,850