Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Intangible Assets, by category
Gross Carrying Amount	$ 199,406		$ 199,406		$ 202,824
Accumulated Amortization	155,026		155,026		149,766
Amortization expense for intangible assets	2,053	$ 2,286	6,208	$ 6,602
Estimated amortization expense for next 5 years
2016	8,000		8,000
2017	5,500		5,500
2018	5,250		5,250
2019	4,750		4,750
2020	4,500		4,500
Customer related
Intangible Assets, by category
Gross Carrying Amount	149,719		149,719		153,287
Accumulated Amortization	113,482		113,482		111,227
Non-compete agreements
Intangible Assets, by category
Gross Carrying Amount	1,096		1,096		1,092
Accumulated Amortization	1,096		1,096		1,092
Patents
Intangible Assets, by category
Gross Carrying Amount	5,783		5,783		5,882
Accumulated Amortization	5,532		5,532		5,495
Technology related
Intangible Assets, by category
Gross Carrying Amount	25,836		25,836		25,559
Accumulated Amortization	25,343		25,343		23,089
Trade names
Intangible Assets, by category
Gross Carrying Amount	8,309		8,309		8,303
Accumulated Amortization	4,455		4,455		4,194
Other
Intangible Assets, by category
Gross Carrying Amount	8,663		8,663		8,701
Accumulated Amortization	$ 5,118		$ 5,118		$ 4,669