Consolidated Condensed Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Net sales	$ 181,027	$ 188,150	$ 358,967	$ 370,091
Cost of sales	87,529	87,122	173,187	166,481
Gross profit	93,498	101,028	185,780	203,610
Selling and administrative expense	73,581	78,234	148,367	156,598
Research and development expense	7,501	6,854	14,043	13,764
Total operating expenses	81,082	85,088	162,410	170,362
Income from operations	12,416	15,940	23,370	33,248
Interest expense	1,489	1,571	2,949	3,032
Income before income taxes	10,927	14,369	20,421	30,216
Provision for income taxes	3,466	4,114	6,648	11,335
Net income	7,461	10,255	13,773	18,881
Comprehensive income	$ 8,630	$ 11,597	$ 4,915	$ 21,174
Per share data:
Basic	$ 0.27	$ 0.38	$ 0.50	$ 0.69
Diluted	0.27	0.37	0.49	0.68
Dividends per share of common stock	$ 0.20	$ 0.20	$ 0.40	$ 0.40
Weighted average common shares:
Basic (shares)	27,620	27,257	27,603	27,303
Diluted (shares)	27,857	27,753	27,839	27,803