Name:	nvl_AccountsPayableForAssetsHeldForSale
Namespace Prefix:	nvl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Accrued liabilities related to a disposal group that is held for sale and anticipated to be sold in less than one year. The liability is expected to be discharged as part of the plan of sale for the asset.

No definition available.

Name:	nvl_AccruedLiabilitiesOfAssetsHeldForSale
Namespace Prefix:	nvl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	nvl_AssetsHeldForSaleAbstract
Namespace Prefix:	nvl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Property Plant and Equipment, Held for Sale

No definition available.

Name:	nvl_PropertyPlantandEquipmentHeldforSale
Namespace Prefix:	nvl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as assets attributable to disposal group held for sale or disposed of, expected to be disposed of within one year or the normal operating cycle, if longer.

Name:	us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as accounts, notes and loans receivable attributable to disposal group held for sale or disposed of.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount classified as other assets attributable to disposal group held for sale or disposed of, expected to be disposed of within one year or the normal operating cycle, if longer.

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as other assets attributable to disposal group held for sale or disposed of, expected to be disposed of after one year or the normal operating cycle, if longer.

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as inventory attributable to disposal group held for sale or disposed of, expected to be disposed of within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1436-107760

Name:	us-gaap_InventoriesPropertyHeldForSaleCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as liabilities attributable to disposal group held for sale or disposed of.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1107-107759

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1436-107760