Note 6 - Income Taxes (Details Textual) $ in Thousands	6 Months Ended
Jun. 30, 2021 USD ($)
Deferred Tax Assets, Valuation Allowance, Total	$ 0
Internal Revenue Service (IRS) [Member]
Open Tax Year	2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 3,600
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Subject to Expiration	3,500
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Subject to Expiration	$ 2,800

Amount of operating loss carryforward subject to expiration, before tax effects, available to reduce future taxable income under enacted tax laws.

No definition available.

+ Details

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Namespace Prefix:	nhtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319

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Period Type:	instant

- Definition

Tax year that remains open to examination under enacted tax laws, in YYYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319

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- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32559-109319

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- Details

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