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)	12 Months Ended
	Jan. 03, 2015	Dec. 28, 2013	Dec. 29, 2012
USANA Nutritionals [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	79.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaNutritionalsMember	80.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaNutritionalsMember	80.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaNutritionalsMember
USANA Foods [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	13.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaFoodsMember	11.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_UsanaFoodsMember	11.00%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	7.00%usna_PercentageOfProductRevenue / us-gaap_ProductOrServiceAxis = usna_SenseBeautifulScienceMember