CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 190,061	$ 139,239	$ 543,040	$ 355,159
Cost of sales	47,128	32,038	134,250	84,351
Gross profit	142,933	107,201	408,790	270,808
Selling, general, and administrative	122,671	89,734	336,458	221,548
Income from operations	20,262	17,467	72,332	49,260
Other income (expense)
Interest income, net	324	361	1,061	940
Other income (expense)	(3)		(11)	178
Other income (expense)	321	361	1,050	1,118
Income from operations before income taxes	20,583	17,828	73,382	50,378
Provision for income taxes	4,681	4,047	15,347	10,242
Net income	$ 15,902	$ 13,781	$ 58,035	$ 40,136
Basic earnings per share
Earnings per share, basic	$ 1.36	$ 1.15	$ 4.91	$ 3.34
Diluted earnings per share
Earnings per share, diluted	$ 1.32	$ 1.14	$ 4.77	$ 3.31
Weighted average shares outstanding -
Basic	11,731	11,954	11,823	12,006
Diluted	12,065	12,097	12,174	12,112
Cash dividends declared per share	$ 0.75	$ 0.48	$ 2.25	$ 1.44