The number of warrants or rights issued during period.

No definition available.

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Namespace Prefix:	ng_
Data Type:	xbrli:sharesItemType
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Period Type:	duration

- Definition

Exercise price per share of warrants or rights issued during period.

+ References

No definition available.

+ Details

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Namespace Prefix:	ng_
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Period Type:	duration

- Definition

Maximum value of company's equity authorized for issuance under equity offering.

+ References

No definition available.

+ Details

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Namespace Prefix:	ng_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Represents the equity offering, option period.

+ References

No definition available.

+ Details

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Namespace Prefix:	ng_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the price share for the overallotment option.

+ References

No definition available.

+ Details

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Namespace Prefix:	ng_
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Balance Type:	na
Period Type:	instant

- Definition

Represents the overallotment option to purchase additional shares.

+ References

No definition available.

+ Details

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Namespace Prefix:	ng_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of expense related to warrants.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	ng_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow for cost incurred directly with the issuance of an equity security.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Period Type:	duration

- Definition

The cash inflow from the additional capital contribution to the entity.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Per share or per unit amount of equity securities issued.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of new stock issued during the period.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Data Type:	xbrli:sharesItemType
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- Definition

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

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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

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Period Type:	instant

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Period Type:

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Period Type:

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Period Type:

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- Details

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- Details

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- Details

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- Details

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- Details

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Note 9 - Equity Transactions (Details Textual) $ / shares in Units, $ in Thousands					3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 05, 2026 USD ($) $ / shares shares	Jun. 05, 2025 USD ($) shares	May 09, 2025 USD ($) $ / shares shares	Apr. 22, 2025 USD ($) $ / shares shares	May 31, 2026 USD ($)	May 31, 2025 USD ($)	May 31, 2026 USD ($) shares	May 31, 2025 USD ($)	Nov. 30, 2025 shares	Jun. 03, 2025 USD ($)
Payments of Stock Issuance Costs					$ (0)	$ 9,734	$ 16,200	$ 9,734
Warrant Expense					(0)	$ 39,607	$ (0)	$ 39,607
Backstop Warrants [Member]
Class of Warrant or Right, Issued During Period \| shares				25,500,000			0		25,500,000
Class of Warrant or Right, Issued During Period, Exercise Price \| $ / shares				$ 3
Warrants and Rights Outstanding, Fair Value Per Share \| $ / shares				$ 1.55
Warrants and Rights Outstanding				$ 39,607
Warrant Expense				$ 39,607
Backstop Warrants [Member] \| Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input				5
Backstop Warrants [Member] \| Measurement Input, Exercise Price [Member]
Warrants and Rights Outstanding, Measurement Input				3
Backstop Warrants [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input				0.0397
Backstop Warrants [Member] \| Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input				0.512
Donlin Gold [Member]
Equity Method Investment, Aggregate Cost					$ 64,000		$ 64,000
Donlin Gold [Member] \| NovaGold Resources Alaska [Member]
Equity Method Investment, Aggregate Cost										$ 200,000
Private Placement [Member]
Stock Issued During Period, Shares, New Issues \| shares	31,020,000		17,173,853
Shares Issued, Price Per Share \| $ / shares	$ 10		$ 3.75
Proceeds from Issuance of Common Stock	$ 310,200
Payments of Stock Issuance Costs	$ 16,200
Public Equity Offering [Member]
Stock Issued During Period, Shares, New Issues \| shares			47,850,000
Shares Issued, Price Per Share \| $ / shares			$ 3.75
Over-Allotment Option [Member]
Stock Issued During Period, Shares, New Issues \| shares		7,177,500
Proceeds from Issuance of Common Stock		$ 26,915
Payments of Stock Issuance Costs		$ 1,434
Equity Offering, Option Period (Day)			30 days
Equity Offering, Option, Shares Available (in shares) \| shares			7,177,500
Equity Offering, Option, Price Per Share \| $ / shares			$ 3.75
May 2025 Offering [Member]
Proceeds from Issuance of Common Stock			$ 243,839
Payments of Stock Issuance Costs			$ 9,734
Offering to Fund Dublin Gold Transaction [Member]
Equity Offering, Maximum Offering Amount				$ 170,000