Consolidated Condensed Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net sales	$ 184,792	$ 169,184	$ 559,426	$ 528,151
Cost of sales	83,583	75,638	258,055	248,825
Gross profit	101,209	93,546	301,371	279,326
Selling and administrative expense	79,009	72,056	251,681	220,423
Research and development expense	8,353	6,652	24,620	20,695
Operating expenses	87,362	78,708	276,301	241,118
Income from operations	13,847	14,838	25,070	38,208
Other expense	0	0	2,942	0
Interest expense	3,861	1,504	11,448	4,453
Income before income taxes	9,986	13,334	10,680	33,755
Provision for income taxes	2,649	4,461	2,724	11,109
Net income	7,337	8,873	7,956	22,646
Comprehensive income	$ 7,901	$ 3,741	$ 10,033	$ 8,656
Per share data:
Basic (in dollars per share)	$ 0.26	$ 0.32	$ 0.29	$ 0.82
Diluted (in dollars per share)	0.26	0.32	0.28	0.81
Dividends per share of common stock (in dollars per share)	$ 0.20	$ 0.20	$ 0.60	$ 0.60
Weighted average common shares:
Basic (shares)	27,818	27,701	27,785	27,636
Diluted (shares)	27,951	27,898	27,946	27,853