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REVISIONS TO PRIOR PERIOD COMPARATIVES (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($)
REVISIONS TO PRIOR PERIOD COMPARATIVES |
Increase to income tax expense | $ 14.8
Increase to deferred tax liabilities | 14.8
Increase to accumulated deficit | $ 14.8

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- Definition The amount of increase to accumulated deficit for correction of accounting errors in prior periods. + References No definition available. + Details
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Balance Type: | debit
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- Definition The amount of increase to deferred tax liabilities for correction of accounting errors in prior periods. + References No definition available. + Details
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Period Type: | duration

X
- Definition The amount of increase to income tax expenses for correction of accounting errors in prior periods. + References No definition available. + Details
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Namespace Prefix: | ngd_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
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Balance Type: | na
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