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v3.10.0.1

Segment Information - Additional Information (Detail) | 12 Months Ended
--- | ---
Dec. 31, 2018 Segment
Disclosure Of Segment Information [abstract] |
Number of reportable segment | 1

X
- Definition Disclosure of segment information. + References No definition available. + Details
Name: | nxe_DisclosureOfSegmentInformationAbstract
Namespace Prefix: | nxe_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of reportable segment. + References No definition available. + Details
Name: | nxe_NumberOfReportableSegment
Namespace Prefix: | nxe_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration