Condensed Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenues	$ 243,273	$ 245,888	$ 824,401	$ 848,856
Cost of sales	119,810	123,454	397,547	427,416
Gross profit	123,463	122,434	426,854	421,440
Selling, general and administrative expenses	120,778	123,649	379,141	387,807
Income (loss) from operations	2,685	(1,215)	47,713	33,633
Foreign currency gain (loss), net	(257)	1,379	181	(1,568)
Interest income	269	178	576	558
Interest expense	(167)	(184)	(539)	(661)
Other income (expense)	54	(1)	187	(108)
Income before income taxes	2,584	157	48,118	31,854
Income tax expense	955	1,690	13,519	7,704
Net income (loss)	1,629	(1,533)	34,599	24,150
Dividends on Series A convertible preferred stock	(3,000)	(3,000)	(9,000)	(9,000)
Dividend equivalents on Series A convertible preferred shares related to redemption value accretion and beneficial conversion feature	(892)	(819)	(2,621)	(2,406)
Net income (loss) attributable to common stockholders	$ (2,263)	$ (5,352)	$ 22,978	$ 12,744
Net income (loss) per common share:
Basic (in dollars per share)	$ (0.03)	$ (0.07)	$ 0.26	$ 0.15
Diluted (in dollars per share)	$ (0.03)	$ (0.07)	$ 0.26	$ 0.14
Weighted average common shares outstanding - basic (shares)	71,895	73,493	73,212	73,323
Weighted average common shares outstanding - diluted (shares)	71,895	73,493	74,160	74,730