CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenue	$ 117,324	$ 75,729	$ 215,920	$ 146,351
Cost of sales	28,525	18,118	52,313	35,848
Gross profit	88,799	57,611	163,607	110,503
Selling, general, and administrative	71,689	46,301	131,814	90,584
Income from operations	17,110	11,310	31,793	19,919
Other income (expense)
Interest income, net	330	141	579	204
Other income (expense)	179	(3)	178	36
Nonoperating income (expense)	509	138	757	240
Income from operations before income taxes	17,619	11,448	32,550	20,159
Provision for income taxes	3,486	3,864	6,195	6,430
Net income	$ 14,133	$ 7,584	$ 26,355	$ 13,729
Basic earnings per share
Earnings Per Share, Basic	$ 1.17	$ 0.64	$ 2.19	$ 1.15
Diluted earnings per share
Earnings Per Share, Diluted	$ 1.16	$ 0.63	$ 2.17	$ 1.14
Weighted average shares outstanding -
Basic	12,037	11,929	12,032	11,915
Diluted	12,174	12,056	12,129	12,044
Cash dividends declared per share	$ 0.48	$ 0.32	$ 0.96	$ 0.64