Post-Employment Benefit Liabilities - Additional Information (Detail)	9 Months Ended
Sep. 30, 2014
Minimum [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Awards for employees	25 years
Maximum [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Awards for employees	40 years

Post employment benefit period of service for award grant.

No definition available.

Name:	nnbr_PostEmploymentBenefitPeriodOfServiceForAwardGrant
Namespace Prefix:	nnbr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration