Consolidated Condensed Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net sales	$ 237,835	$ 233,590	$ 609,631	$ 690,232
Cost of sales	104,137	103,479	284,845	307,492
Gross profit	133,698	130,111	324,786	382,740
Selling and administrative expense	94,380	98,187	274,721	298,140
Research and development expense	9,936	10,985	28,756	33,366
Operating expenses	104,316	109,172	303,477	331,506
Income from operations	29,382	20,939	21,309	51,234
Interest expense	11,943	11,174	32,938	32,382
Other expense	89	321	266	4,867
Income (loss) before income taxes	17,350	9,444	(11,895)	13,985
Provision for income taxes	10,500	2,474	2,728	299
Net income (loss)	6,850	6,970	(14,623)	13,686
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 8,976	$ 4,661	$ (16,858)	$ 11,508
Per share data:
Basic (in dollars per share)	$ 0.24	$ 0.25	$ (0.51)	$ 0.48
Diluted (in dollars per share)	$ 0.23	$ 0.23	$ (0.51)	$ 0.47
Weighted average common shares:
Basic (shares)	28,583	28,353	28,529	28,280
Diluted (shares)	29,426	29,792	28,529	29,354