GOLD STREAM OBLIGATION (Details Textual) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) Ounces
Disclosure of gold stream obligation [Line Items]
Transaction price allocated to remaining performance obligations	$ 175.0
Gold stream obligation, rate of gold production to be delivered for initial threshold	6.50%
Gold stream obligation initial threshold quantity \| Ounces	230,000
Gold stream obligation rate of gold production to be delivered after initial threshold	3.25%
Gold stream obligation, rate of silver production to be delivered for initial threshold	60.00%
Gold stream obligation, silver production, initial threshold quantity \| Ounces	3,100,000
Gold stream obligation, rate of silver production to be delivered after initial threshold	30.00%
Gold stream obligations, proceeds from gold and silver	$ 2.4
Average spot rate of gold or silver	25.00%
Term of the agreement	40 years
Unpaid accruals	$ 1.3
Bottom of range [member]
Disclosure of gold stream obligation [Line Items]
Maximum leverage ratio	3.5
Top of range [member]
Disclosure of gold stream obligation [Line Items]
Maximum leverage ratio	4.0

The amount of the transaction price allocated to the performance obligations that are unsatisfied (or partially unsatisfied) as of the end of the reporting period. The transaction price is the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to a customer, excluding amounts collected on behalf of third parties (for example, some sales taxes). [Refer: Performance obligations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 15
-IssueDate 2017-01-01
-Paragraph 120
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=15&date=2017-03-01&anchor=para_120_a&doctype=Standard
-URIDate 2017-03-09

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

It represents the price, Royal Gold will pay New Gold for the ounces delivered.

+ References

No definition available.

+ Details

Name:	ngd_AverageSpotRateOfGoldOrSilver
Namespace Prefix:	ngd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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Namespace Prefix:	ngd_
Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Represents the first threshold quantity of gold production after entering into the transaction.

+ References

No definition available.

+ Details

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Namespace Prefix:	ngd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage rate of gold production which will be delivered for the initial threshold after initial threshold.

+ References

No definition available.

+ Details

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Namespace Prefix:	ngd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage rate of gold production which will be delivered for the initial threshold after entering into the transaction.

+ References

No definition available.

+ Details

Name:	ngd_GoldStreamObligationRateOfGoldProductionToBeDeliveredForInitialThreshold
Namespace Prefix:	ngd_
Data Type:	num:percentItemType
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Period Type:	instant

- Definition

The percentage rate of silver production which will be delivered for the initial threshold after initial threshold.

+ References

No definition available.

+ Details

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Namespace Prefix:	ngd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage rate of Silver production which will be delivered for the initial threshold after entering into the transaction.

+ References

No definition available.

+ Details

Name:	ngd_GoldStreamObligationRateOfSilverProductionToBeDeliveredForInitialThreshold
Namespace Prefix:	ngd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the first threshold quantity of silver production after entering into the transaction.

+ References

No definition available.

+ Details

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Namespace Prefix:	ngd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

It represents the value of proceeds received from the delivery of gold and silver under the gold stream obligations.

+ References

No definition available.

+ Details

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Namespace Prefix:	ngd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Ratio of maximum coverage relating to Credit Facility.

+ References

No definition available.

+ Details

Name:	ngd_MaximumLeverageRatio
Namespace Prefix:	ngd_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The term of the agreement which is entered with the wholly-owned subsidiary.

+ References

No definition available.

+ Details

Name:	ngd_TermOfAgreement
Namespace Prefix:	ngd_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Unpaid accruals related to the settlement of the stream obligation.

+ References

No definition available.

+ Details

Name:	ngd_UnpaidAccruals
Namespace Prefix:	ngd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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- Details

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