Exercise price per share or per unit of warrants or rights outstanding.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares.

+ References

No definition available.

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Face amount or stated value per share of common stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockParOrStatedValuePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

+ References

+ Details

Name:	us-gaap_CommonStockSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

+ Details

Name:	us-gaap_DividendsCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_PreferredStockParOrStatedValuePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_PreferredStockSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_PreferredStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

+ References

No definition available.

+ Details

Name:	us-gaap_WarrantsAndRightsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_WarrantsAndRightsOutstandingMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The exercise price per share or per unit of warrants necessary to be entitled to receive cash consideration equal to Black-Scholes valuation, as defined in the warrant, in the event of a Fundamental Transaction (a transfer of ownership of the Company as defined in the warrant)

+ References

No definition available.

+ Details

Name:	vxrt_WarrantExercisePriceToBeEntitledToReceiveCashConsiderationFundamentalTransaction
Namespace Prefix:	vxrt_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vxrt_TheMarch2020OfferingPlacementAgentWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputSharePriceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputRiskFreeInterestRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedTermMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vxrt_FirstSetOfWarrantsExpiringSeptember2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vxrt_SecondSetOfWarrantsExpiringApril2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vxrt_FirstSetOfWarrantsExpiringApril2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vxrt_WarrantsExpiringMarch2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vxrt_WarrantsExpiringMarch2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 10 - Stockholders' Equity (Details Textual)	6 Months Ended
Note 10 - Stockholders' Equity (Details Textual)	Jun. 30, 2020 USD ($)	Sep. 30, 2020 $ / shares shares	Jun. 08, 2020 $ / shares shares	Jun. 07, 2020 $ / shares shares	Mar. 02, 2020 USD ($) yr $ / shares shares	Dec. 31, 2019 $ / shares shares
Preferred Stock, Shares Authorized (in shares) \| shares		5,000,000				5,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001	$ 0.0001	$ 0.10		$ 0.0001
Preferred Stock, Shares Outstanding, Ending Balance (in shares) \| shares		0				0
Common Stock, Shares Authorized (in shares) \| shares		150,000,000	150,000,000	100,000,000		150,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001	$ 0.0001	$ 0.10		$ 0.0001
Dividends, Total \| $	$ 0
The March 2020 Offering Placement Agent Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) \| shares					280,000
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) \| shares					1
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 3.125
Warrants and Rights Outstanding, Term (Year)					5 years
Warrants and Rights Outstanding \| $					$ 453,000
The March 2020 Offering Placement Agent Warrants [Member] \| Measurement Input, Share Price [Member]
Warrants and Rights Outstanding, Measurement Input					2.34
The March 2020 Offering Placement Agent Warrants [Member] \| Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input					0.98
The March 2020 Offering Placement Agent Warrants [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input					0.0088
The March 2020 Offering Placement Agent Warrants [Member] \| Measurement Input, Discount Rate [Member]
Warrants and Rights Outstanding, Measurement Input					0
The March 2020 Offering Placement Agent Warrants [Member] \| Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input \| yr					4.99
First Set of Warrants Expiring September 2024 [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		0.30
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		0.30
Second Set of Warrants Expiring April 2024 [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		1.375
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		0.375
First Set of Warrants Expiring April 2024 [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		1.10
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		1.10
Warrants Expiring March 2025 [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		2.50
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		2.50
Warrants Expiring March 2024 [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		3.125
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		$ 3.125