Condensed Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net sales	$ 260,598	$ 296,767	$ 789,604	$ 890,225
Cost of sales	47,819	51,877	140,214	151,243
Gross profit	212,779	244,890	649,390	738,982
Operating expenses:
Associate incentives	111,059	130,264	345,100	392,416
Selling, general and administrative	66,262	69,112	202,671	206,781
Total operating expenses	177,321	199,376	547,771	599,197
Earnings from operations	35,458	45,514	101,619	139,785
Other income (expense):
Interest income	966	1,269	3,751	3,140
Interest expense	(22)	(8)	(44)	(27)
Other, net	(514)	(249)	(632)	(851)
Other income (expense), net	430	1,012	3,075	2,262
Earnings before income taxes	35,888	46,526	104,694	142,047
Income taxes	11,666	15,486	34,922	48,154
Net earnings	$ 24,222	$ 31,040	$ 69,772	$ 93,893
Earnings per common share
Basic	$ 1.09	$ 1.28	$ 3.04	$ 3.88
Diluted	$ 1.09	$ 1.24	$ 3.01	$ 3.80
Weighted average common shares outstanding
Basic	22,180	24,269	22,969	24,179
Diluted	22,223	25,001	23,173	24,705
Comprehensive income:
Net earnings	$ 24,222	$ 31,040	$ 69,772	$ 93,893
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(6,186)	(6,381)	(7,004)	(10,087)
Tax benefit (expense) related to foreign currency translation adjustment	422	344	(630)	1,612
Other comprehensive income (loss), net of tax	(5,764)	(6,037)	(7,634)	(8,475)
Comprehensive income	$ 18,458	$ 25,003	$ 62,138	$ 85,418