IMPAIRMENT (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Impairment [Line Items]
Impairment loss net of deferred tax recovery	$ 181.0
Impairment loss	$ 268.4	$ 6.4
Rio Figueroa NSR [Member]
Impairment [Line Items]
NSR royalty on production, percentage	3.00%
Weighted average [member]
Impairment [Line Items]
Discount rate used in current estimate of value in use	4.00%	5.50%

The discount rate used in the current estimate of the present value of the future cash flows expected to be derived from an asset or cash-generating unit.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 130
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_130_g&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_DescriptionOfDiscountRatesUsedInCurrentEstimateOfValueInUse
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount recognised as a reduction of the carrying amount of an asset or cash-generating unit to its recoverable amount. [Refer: Carrying amount [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 130
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_130_b&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 130
-Subparagraph d
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_130_d_ii&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_ImpairmentLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	ngd_ImpairmentLineItems
Namespace Prefix:	ngd_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount recognised as a reduction of the carrying amount of an asset or cash-generating unit to its recoverable amount, net of deferred tax recovery.

+ References

No definition available.

+ Details

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

- Definition

It represents the NSR royalty is on the production of the Rio Figueroa property.

+ References

No definition available.

+ Details

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

- Details

Name:	ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis=ngd_RioFigueroaNsrMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: