USANA Health Sciences, Inc. Annual report pursuant to Section 13 and 15(d)

Segment Information (Schedule Of Revenues From External Customers By Geographical Areas) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Sales to External Customers	$ 271,298	$ 260,598	$ 256,016	$ 272,990	$ 299,023	$ 296,767	$ 301,460	$ 291,998	$ 1,060,902	$ 1,189,248	$ 1,047,265
Greater China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Sales to External Customers									535,995	654,394	546,777
Southeast Asia Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Sales to External Customers									220,085	225,469	205,289
North Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Sales to External Customers									96,187	76,720	58,376
Asia Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Sales to External Customers									852,267	956,583	810,442
Americas And Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Sales to External Customers									$ 208,635	$ 232,665	$ 236,823