The maturities of lease liabilities are as follows at March 31, 2023: (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Leases
Total remaining lease payments	$ 338
Less portion of payments representing interest	(91)
Present value of lease payments	247
Less current portion of lease payments	(70)
Non current lease liability	$ 177

No definition available.

Name:	niobf_DisclosureLeasesAbstract
Namespace Prefix:	niobf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The element represents less amount of payments representing interest.

+ References

No definition available.

+ Details

Name:	niobf_LessAmountOfPaymentsRepresentingInterest
Namespace Prefix:	niobf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The element represents less current portion of lease payments.

+ References

No definition available.

+ Details

Name:	niobf_LessCurrentPortionOfLeasePayments
Namespace Prefix:	niobf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The element represents non current lease liability.

+ References

No definition available.

+ Details

Name:	niobf_NonCurrentLeaseLiability
Namespace Prefix:	niobf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918701-209980

+ Details

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

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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