| Document And Entity Information
|
9 Months Ended | |
|---|---|---|
| Oct. 02, 2011
|
Nov. 01, 2011
|
|
| Document And Entity Information [Abstract] | ||
| Document Type | 10-Q | |
| Amendment Flag | false | |
| Document Period End Date | Oct. 02, 2011 | |
| Document Fiscal Period Focus | Q3 | |
| Document Fiscal Year Focus | 2011 | |
| Entity Registrant Name | NATIONAL PRESTO INDUSTRIES INC | |
| Entity Central Index Key | 0000080172 | |
| Current Fiscal Year End Date | --12-31 | |
| Entity Filer Category | Accelerated Filer | |
| Entity Common Stock, Shares Outstanding | 6,873,647 |