Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Intangible Assets, by category
Gross Carrying Amount	$ 199,095		$ 199,095		$ 195,074
Accumulated Amortization	159,123		159,123		153,507
Amortization expense for intangible assets	1,280	$ 2,050	2,598	$ 4,155
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	150,373		150,373		146,840
Accumulated Amortization	117,365		117,365		112,610
Patents
Intangible Assets, by category
Gross Carrying Amount	5,783		5,783		5,729
Accumulated Amortization	5,649		5,649		5,534
Technology related
Intangible Assets, by category
Gross Carrying Amount	25,918		25,918		25,687
Accumulated Amortization	25,907		25,907		25,634
Trade names
Intangible Assets, by category
Gross Carrying Amount	8,312		8,312		8,306
Accumulated Amortization	4,687		4,687		4,529
Other
Intangible Assets, by category
Gross Carrying Amount	8,709		8,709		8,512
Accumulated Amortization	$ 5,515		$ 5,515		$ 5,200