Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Net sales	$ 83,644us-gaap_SalesRevenueNet	$ 83,496us-gaap_SalesRevenueNet
Cost of sales	53,569us-gaap_CostOfGoodsAndServicesSold	54,545us-gaap_CostOfGoodsAndServicesSold
Gross margin	30,075us-gaap_GrossProfit	28,951us-gaap_GrossProfit
Selling, engineering and administration	23,022	21,261
Operating earnings	7,053us-gaap_OperatingIncomeLoss	7,690us-gaap_OperatingIncomeLoss
Interest expense, net	317us-gaap_InterestIncomeExpenseNet	291us-gaap_InterestIncomeExpenseNet
Earnings before income taxes	6,736	7,399
Provision for income taxes	2,509us-gaap_IncomeTaxExpenseBenefit	2,767us-gaap_IncomeTaxExpenseBenefit
Net earnings	$ 4,227us-gaap_NetIncomeLoss	$ 4,632us-gaap_NetIncomeLoss
Earnings per share: (in dollars per share)
Basic	$ 0.29us-gaap_EarningsPerShareBasic	$ 0.33us-gaap_EarningsPerShareBasic
Diluted	$ 0.29us-gaap_EarningsPerShareDiluted	$ 0.32us-gaap_EarningsPerShareDiluted
Dividends declared per common share	$ 0.19	$ 0.18
Shares used in computation of earnings per share: (in shares)
Basic	14,332,775	14,240,220
Impact of dilutive securities	74,232	89,977
Diluted	14,407,007	14,330,197

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770