Segment Information (Schedule Of Revenue Percentage By Product) (Details)	12 Months Ended
	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
USANA Nutritionals [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	83.00%	81.00%	79.00%
USANA Foods [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	10.00%	11.00%	13.00%
Sense - Beautiful Science [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	6.00%	7.00%	7.00%