Segments Table (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Sales	$ 211,481	$ 222,022	$ 221,962	$ 212,055	$ 211,072	$ 212,918	$ 201,183	$ 194,909	$ 867,520	$ 820,082	$ 746,665
Operating income for reportable segments	184,183				165,313				184,183	165,313	158,895
Segment assets	709,665				722,126				709,665	722,126	692,028
Long-Lived Assets	137,294				142,443				137,294	142,443	137,303
Capital Expenditures									12,886	10,872	9,954
Depreciation									12,196	12,477	12,432
Non Domestic [Member]
Segment Reporting Information [Line Items]
Net Sales									50,800	49,200	35,800
Long-Lived Assets	4,500				4,900				4,500	4,900	4,900
North America [Member]
Segment Reporting Information [Line Items]
Net Sales									383,471	356,598	336,174
Operating income for reportable segments	88,276				77,694				88,276	77,694	77,833
Segment assets	317,934				324,260				317,934	324,260	321,404
Long-Lived Assets	84,876				88,818				84,876	88,818	86,775
Capital Expenditures									4,574	3,919	2,918
Depreciation									5,770	5,791	5,672
EMEA [Member]
Segment Reporting Information [Line Items]
Net Sales									233,597	226,243	200,917
Operating income for reportable segments	35,970				35,350				35,970	35,350	33,810
Segment assets	157,111				177,267				157,111	177,267	147,021
Long-Lived Assets	26,239				28,507				26,239	28,507	25,630
Capital Expenditures									2,081	3,936	3,263
Depreciation									3,434	3,368	3,323
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Sales									214,157	201,008	179,131
Operating income for reportable segments	56,056				48,342				56,056	48,342	45,866
Segment assets	212,545				196,891				212,545	196,891	200,218
Long-Lived Assets	23,650				22,427				23,650	22,427	22,040
Capital Expenditures									6,059	2,458	3,269
Depreciation									2,552	2,669	2,765
South America [Member]
Segment Reporting Information [Line Items]
Net Sales									36,295	36,233	30,443
Operating income for reportable segments	3,881				3,927				3,881	3,927	1,386
Segment assets	22,075				23,708				22,075	23,708	23,385
Long-Lived Assets	$ 2,529				$ 2,691				2,529	2,691	2,858
Capital Expenditures									172	559	504
Depreciation									440	649	672
Intersegment Sales Elimination [Member] | North America [Member]
Segment Reporting Information [Line Items]
Net Sales									9,700	9,400	8,300
Intersegment Sales Elimination [Member] | EMEA [Member]
Segment Reporting Information [Line Items]
Net Sales									22,000	22,000	18,100
Intersegment Sales Elimination [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Sales									500	400	700
Intersegment Sales Elimination [Member] | South America [Member]
Segment Reporting Information [Line Items]
Net Sales									$ 100	$ 100	$ 100