Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Intangible Assets, by category
Gross Carrying Amount	$ 200,730		$ 200,730		$ 202,824
Accumulated Amortization	153,652		153,652		149,766
Amortization expense for intangible assets	2,050	$ 2,179	4,155	$ 4,316
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	150,916		150,916		153,287
Accumulated Amortization	112,933		112,933		111,227
Non-compete agreements
Intangible Assets, by category
Gross Carrying Amount	1,095		1,095		1,092
Accumulated Amortization	1,095		1,095		1,092
Patents
Intangible Assets, by category
Gross Carrying Amount	5,827		5,827		5,882
Accumulated Amortization	5,519		5,519		5,495
Technology related
Intangible Assets, by category
Gross Carrying Amount	25,892		25,892		25,559
Accumulated Amortization	24,727		24,727		23,089
Trade names
Intangible Assets, by category
Gross Carrying Amount	8,310		8,310		8,303
Accumulated Amortization	4,379		4,379		4,194
Other
Intangible Assets, by category
Gross Carrying Amount	8,690		8,690		8,701
Accumulated Amortization	$ 4,999		$ 4,999		$ 4,669