Cash settlement of interest rate hedges.

No definition available.

Name:	nnbr_CashSettlementOfInterestRateHedges
Namespace Prefix:	nnbr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e845-128460

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e848-128460

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e1043-128460

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=nnbr_DrtMedicalLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Subsequent Events - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended
	Oct. 27, 2017	Oct. 02, 2017	Sep. 30, 2017	Sep. 30, 2017
Subsequent Event [Line Items]
Acquisition related costs			$ 619	$ 619
DRT Medical, LLC, ("DRT Medical") [Member]
Subsequent Event [Line Items]
Date of acquisition				Oct. 02, 2017
Acquisition related costs			$ 600	$ 600
Subsequent Event [Member]
Subsequent Event [Line Items]
Cash payments related to the interest rate swap	$ 1,300
Subsequent Event [Member] \| DRT Medical, LLC, ("DRT Medical") [Member]
Subsequent Event [Line Items]
Cash payment to acquire business		$ 38,600
Acquisition percentage		100.00%