XML 70 R53.htm IDEA: XBRL DOCUMENT
v3.20.1

Significant Accounting Policies - Additional Information (Detail) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jan. 01, 2019 USD ($)
Significant Accounting Policies [Line Items] |  |  |  |
Number of manufacturing facilities | 50 |  |  |
Maturity period of highly liquid investments | three months or less |  |  |
Goodwill impairment | $ 0 | $ 182,542 | $ 0 |
Land and buildings | Minimum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful lives | 15 years |  |  |
Land and buildings | Maximum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful lives | 40 years |  |  |
Machinery and equipment | Minimum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful lives | 3 years |  |  |
Machinery and equipment | Maximum |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful lives | 12 years |  |  |
Accounting Standards Update 2016-02 |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  | $ 100
Wuxi Weifu Autocam Precision Machinery Company, Ltd. |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Investment in joint venture | 49.00% |  |  |

X
- Definition Maturity period of highly liquid investments. + References No definition available. + Details
Name: | nnbr_MaturityPeriodOfHighlyLiquidInvestments
Namespace Prefix: | nnbr_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of manufacturing facilities. + References No definition available. + Details
Name: | nnbr_NumberOfManufacturingFacilities
Namespace Prefix: | nnbr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | nnbr_SignificantAccountingPoliciesLineItems
Namespace Prefix: | nnbr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption. + References No definition available. + Details
Name: | us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_MachineryAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=nnbr_WuxiWeifuAutocamPrecisionMachineryCompanyLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |