Condensed Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 358,899	$ 328,004	$ 654,848	$ 611,152
Cost of sales	169,520	146,604	327,854	289,879
Gross profit	189,379	181,400	326,994	321,273
Selling, general and administrative expenses	141,548	144,336	246,585	258,287
Income from operations	47,831	37,064	80,409	62,986
Foreign currency gains (losses), net	(261)	283	(1,478)	1,354
Interest income	131	146	326	425
Interest expense	(2,421)	(132)	(4,238)	(245)
Other income (expense), net	(604)	16	(14)	69
Income before income taxes	44,676	37,377	75,005	64,589
Income tax expense	5,478	3,000	11,097	13,758
Net income	39,198	34,377	63,908	50,831
Dividends on Series A convertible preferred stock	0	(3,000)	0	(6,000)
Dividend equivalents on Series A convertible preferred stock related to redemption value accretion and beneficial conversion feature	0	(951)	0	(1,882)
Net income attributable to common stockholders	$ 39,198	$ 30,426	$ 63,908	$ 42,949
Net income per common share:
Basic (in dollars per share)	$ 0.55	$ 0.37	$ 0.89	$ 0.52
Diluted (in dollars per share)	$ 0.55	$ 0.35	$ 0.87	$ 0.51
Weighted average common shares outstanding:
Basic (shares)	70,936	68,153	71,967	68,427
Diluted (shares)	71,915	71,467	73,369	70,462