Condensed Consolidated Statements of Income (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Condensed Consolidated Statements of Income (unaudited) [Abstract]
Net sales	$ 247,833	$ 251,967
Cost of sales	189,266	193,371
Gross profit	58,567	58,596
Selling, general, administrative and engineering expenses	40,367	40,143
Income from operations	18,200	18,453
Interest expense	70	47
Other income, net of expenses	752	849
Income from continuing operations before income taxes	18,882	19,255
Income taxes on continuing operations	5,631	7,231
Net income from continuing operations	13,251	12,024
Income from discontinued operations, net of tax	0	234
Net income	13,251	12,258
Net income attributable to non-controlling interest	80	13
Net income attributable to controlling interest	$ 13,171	$ 12,245
Net income attributable to controlling interest from continuing operations:
Basic (in dollars per share)	$ 0.58	$ 0.53
Diluted (in dollars per share)	$ 0.57	$ 0.52
Income from discontinued operations, net of tax
Basic (in dollars per share)	$ 0	$ 0.01
Diluted (in dollars per share)	$ 0	$ 0.01
Net income attributable to controlling interest:
Basic (in dollars per share)	$ 0.58	$ 0.54
Diluted (in dollars per share)	$ 0.57	$ 0.53
Weighted average number of common shares outstanding:
Basic (in shares)	22,723	22,643
Diluted (in shares)	23,080	23,054