| Document and Entity Information | Mar. 22, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | NN INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000918541 |
| Current Fiscal Year End Date | --12-31 |
| Document Type | 8-K |
| Document Period End Date | Mar. 22, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 000-23486 |
| Entity Tax Identification Number | 62-1096725 |
| Entity Address, Address Line One | 6210 Ardrey Kell Road |
| Entity Address, City or Town | Charlotte |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 28277 |
| City Area Code | (980) |
| Local Phone Number | 264-4300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.01 |
| Trading Symbol | NNBR |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
