The number of warrants or rights issued during period.

No definition available.

Name:	ng_ClassOfWarrantOrRightIssuedDuringPeriod
Namespace Prefix:	ng_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

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Balance Type:	debit
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- Definition

Amount of transactions with related party during the financial reporting period.

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- Definition

Number of new stock issued during the period.

+ References

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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Note 14 - Related Party Transactions (Details Textual) - USD ($) $ in Thousands				3 Months Ended		6 Months Ended	12 Months Ended
	May 31, 2026	May 09, 2025	Apr. 22, 2025	May 31, 2026	May 31, 2025	May 31, 2026	Nov. 30, 2025
Public Equity Offering [Member]
Stock Issued During Period, Shares, New Issues		47,850,000
Backstop Warrants [Member]
Warrants and Rights Outstanding			$ 39,607
Class of Warrant or Right, Issued During Period			25,500,000			0	25,500,000
Donlin Gold [Member]
Accounts Receivable, after Allowance for Credit Loss	$ 267			$ 267		$ 267	$ 1,044
Electrum [Member] \| Public Equity Offering [Member]
Stock Issued During Period, Shares, New Issues		13,333,334
Proceeds from Issuance of Common Stock		$ 50,000
Electrum [Member] \| Backstop Warrants [Member]
Warrants and Rights Outstanding			$ 9,902
Class of Warrant or Right, Issued During Period			6,375,000,000
Management and Administrative Services Provided [Member] \| Donlin Gold [Member]
Related Party Transaction, Amounts of Transaction	$ 332			$ 461	$ 156	$ 891