Segments Table (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net sales	$ 191,245	$ 190,428	$ 186,915	$ 178,077	$ 183,275	$ 189,224	$ 183,726	$ 181,330	$ 746,665	$ 737,555	$ 765,860
Operating income for reportable segments	158,378				154,662				158,378	154,662	149,024
Segment assets	692,028				680,727				692,028	680,727	664,376
Long-Lived Assets	137,303				140,191				137,303	140,191	141,256
Capital Expenditures									9,954	11,033	13,052
Depreciation									12,432	12,196	12,073
Non Domestic [Member]
Segment Reporting Information [Line Items]
Net sales									35,800	34,000	35,500
Long-Lived Assets	4,900				2,700				4,900	2,700	3,100
North America [Member]
Segment Reporting Information [Line Items]
Net sales									336,174	344,248	334,400
Operating income for reportable segments	77,492				79,791				77,492	79,791	68,296
Segment assets	321,404				317,082				321,404	317,082	340,139
Long-Lived Assets	86,775				87,421				86,775	87,421	92,319
Capital Expenditures									2,918	4,166	3,658
Depreciation									5,672	5,577	5,231
(Increase) Decrease In Segment Assets										3,200	200
EMEA [Member]
Segment Reporting Information [Line Items]
Net sales									200,917	179,717	195,309
Operating income for reportable segments	33,634				27,979				33,634	27,979	32,589
Segment assets	147,021				162,647				147,021	162,647	123,916
Long-Lived Assets	25,630				27,101				25,630	27,101	20,634
Capital Expenditures									3,263	3,081	4,811
Depreciation									3,323	2,975	3,069
(Increase) Decrease In Segment Assets										1,100	400
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales									179,131	181,056	185,974
Operating income for reportable segments	45,866				45,107				45,866	45,107	43,847
Segment assets	200,218				181,389				200,218	181,389	170,444
Long-Lived Assets	22,040				23,096				22,040	23,096	24,392
Capital Expenditures									3,269	3,169	3,202
Depreciation									2,765	2,812	2,713
(Increase) Decrease In Segment Assets										300	100
South America [Member]
Segment Reporting Information [Line Items]
Net sales									30,443	32,534	50,177
Operating income for reportable segments	1,386				1,785				1,386	1,785	4,292
Segment assets	23,385				19,609				23,385	19,609	29,877
Long-Lived Assets	$ 2,858				$ 2,573				2,858	2,573	3,911
Capital Expenditures									504	617	1,381
Depreciation									672	832	1,060
(Increase) Decrease In Segment Assets										200	400
Intersegment Sales Elimination [Member] | North America [Member]
Segment Reporting Information [Line Items]
Net sales									8,300	9,100	8,000
Intersegment Sales Elimination [Member] | EMEA [Member]
Segment Reporting Information [Line Items]
Net sales									18,100	17,800	22,300
Intersegment Sales Elimination [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales									700	1,000	400
Intersegment Sales Elimination [Member] | South America [Member]
Segment Reporting Information [Line Items]
Net sales									$ 100	$ 100	$ 100