Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 1,078,809	$ 977,025	$ 860,661
Cost of sales	598,290	533,644	450,781
Gross profit	480,519	443,381	409,880
Operating expenses:
Research and development and other engineering	43,056	47,616	46,248
Selling	109,931	114,903	98,343
General and administrative	159,093	143,107	124,859
Total operating expenses	312,080	305,626	269,450
Net gain on disposal of assets	(10,579)	(160)	(780)
Impairment of goodwill	6,686	0	0
Income from operations	172,332	137,915	141,210
Loss in equity investment, before tax	(63)	(86)	0
Foreign exchange gain (loss), net	430	1,252	(1,733)
Interest Income (Expense), Net	(571)	(788)	(577)
Gain on bargain purchase of a business	0	(6,336)	0
Loss on disposal of a business	0	(211)	0
Income before taxes	172,128	144,418	138,900
Provision for income taxes	45,495	51,801	49,166
Net income	$ 126,633	$ 92,617	$ 89,734
Earnings per share of common stock:
Basic	$ 2.74	$ 1.95	$ 1.87
Diluted	$ 2.72	$ 1.94	$ 1.86
Weighted average number of shares of common stock outstanding
Basic (in shares)	46,213	47,486	48,084
Diluted (in shares)	46,540	47,774	48,295