Consolidated Condensed Statements of Operations (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidated Condensed Statements of Operations [Abstract]
Net sales	$ 81,974	$ 75,148	$ 158,207	$ 132,507
Cost of sales	51,773	47,928	99,142	84,850
Gross margin	30,201	27,220	59,065	47,657
Selling, engineering and administration	18,846	14,943	37,522	30,142
Operating earnings	11,355	12,277	21,543	17,515
Interest expense	238	96	443	208
Earnings before income taxes	11,117	12,181	21,100	17,307
Provision for income taxes	3,675	4,347	7,409	6,213
Net earnings	$ 7,442	$ 7,834	$ 13,691	$ 11,094
Earnings per share:
Basic	$ 0.52	$ 0.52	$ 0.94	$ 0.74
Diluted	$ 0.52	$ 0.52	$ 0.94	$ 0.74
Dividends declared - Common stock	$ 0.16	$ 0.14	$ 0.32	$ 0.28
Shares used in computation of earnings per share:
Basic	14,234,900	14,962,314	14,527,328	14,943,502
Impact of dilutive securities	72,332	90,478	68,785	91,955
Diluted	14,307,232	15,052,792	14,596,113	15,035,457