Segments Table (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 211,072	$ 212,918	$ 201,183	$ 194,909	$ 191,245	$ 190,428	$ 186,915	$ 178,077	$ 820,082	$ 746,665	$ 737,555
Operating income for reportable segments	165,313				158,895				165,313	158,895	155,367
Segment assets	722,126				692,028				722,126	692,028	680,727
Long-Lived Assets	142,443				137,303				142,443	137,303	140,191
Capital Expenditures									10,872	9,954	11,033
Depreciation									12,477	12,432	12,196
Non Domestic [Member]
Segment Reporting Information [Line Items]
Net sales									49,200	35,800	34,000
Long-Lived Assets	4,900				4,900				4,900	4,900	2,700
North America [Member]
Segment Reporting Information [Line Items]
Net sales									356,598	336,174	344,248
Operating income for reportable segments	77,694				77,833				77,694	77,833	80,239
Segment assets	324,260				321,404				324,260	321,404	317,082
Long-Lived Assets	88,818				86,775				88,818	86,775	87,421
Capital Expenditures									3,919	2,918	4,166
Depreciation									5,791	5,672	5,577
EMEA [Member]
Segment Reporting Information [Line Items]
Net sales									226,243	200,917	179,717
Operating income for reportable segments	35,350				33,810				35,350	33,810	28,236
Segment assets	177,267				147,021				177,267	147,021	162,647
Long-Lived Assets	28,507				25,630				28,507	25,630	27,101
Capital Expenditures									3,936	3,263	3,081
Depreciation									3,368	3,323	2,975
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales									201,008	179,131	181,056
Operating income for reportable segments	48,342				45,866				48,342	45,866	45,107
Segment assets	196,891				200,218				196,891	200,218	181,389
Long-Lived Assets	22,427				22,040				22,427	22,040	23,096
Capital Expenditures									2,458	3,269	3,169
Depreciation									2,669	2,765	2,812
South America [Member]
Segment Reporting Information [Line Items]
Net sales									36,233	30,443	32,534
Operating income for reportable segments	3,927				1,386				3,927	1,386	1,785
Segment assets	23,708				23,385				23,708	23,385	19,609
Long-Lived Assets	$ 2,691				$ 2,858				2,691	2,858	2,573
Capital Expenditures									559	504	617
Depreciation									649	672	832
Intersegment Sales Elimination [Member] | North America [Member]
Segment Reporting Information [Line Items]
Net sales									9,400	8,300	9,100
Intersegment Sales Elimination [Member] | EMEA [Member]
Segment Reporting Information [Line Items]
Net sales									22,000	18,100	17,800
Intersegment Sales Elimination [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales									400	700	1,000
Intersegment Sales Elimination [Member] | South America [Member]
Segment Reporting Information [Line Items]
Net sales									$ 100	$ 100	$ 100