Segment Information (Schedule Of Revenue Percentage By Product) (Details)	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
USANA Nutritionals [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	83.00%	83.00%	82.00%	84.00%
USANA Foods [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	9.00%	9.00%	9.00%	9.00%
Sense - Beautiful Science [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	2.00%	6.00%	4.00%	6.00%
Celavive [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	5.00%		4.00%