Segment Information (Percentage Of Total Product Revenue Contributed By Company's Nutritional And Care Products) (Details)

v2.4.1.9

Segment Information (Percentage Of Total Product Revenue Contributed By Company's Nutritional And Care Products) (Details)	3 Months Ended
	Apr. 04, 2015	Mar. 29, 2014
USANA Nutritionals [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	81.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaNutritionalsMember	79.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaNutritionalsMember
USANA Foods [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	11.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaFoodsMember	13.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaFoodsMember
Sense - Beautiful Science [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	7.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_SenseBeautifulScienceMember	6.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_SenseBeautifulScienceMember