Document And Entity Information	3 Months Ended
	Mar. 30, 2014	May 01, 2014
Document And Entity Information [Abstract]
Document Type	10-Q/A
Amendment Flag	true
Document Period End Date	Mar. 30, 2014
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2014
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		6,909,333
Amendment Description	The purpose of the Amendment No. 1 on Form 10–Q/A to National Presto Industries, Inc.'s quarterly report on Form 10–Q for the quarter ended March 30, 2014, filed with the Securities and Exchange Commission on May 9, 2014 (the "Form 10–Q"), is solely to furnish a revised Exhibit 101, eXtensible Business Reporting Language ("XBRL") data files, to the Form 10–Q in accordance with Rule 405 of Regulation S–T. The revised Exhibit 101 contains certain data related to the Notes to the Consolidated Financial Statements that were omitted from the original filing, due to an apparent XBRL software or hardware malfunction. No other changes have been made to the Form 10–Q. This Amendment No. 1 speaks as of the original filing date of the form 10–Q, does not reflect events that may have occurred subsequent to the original filing date and does not modify or update in any way disclosures made in the original Form 10–Q. Pursuant to rule 406T of Regulation S–T, the interactive data files on Exhibit 101 hereto are deemed not filed or part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, as amended, are deemed not filed for purposes of Section 18 of the Securities Act of 1934, as amended, and otherwise are not subject to liability under those sections.
Entity Current Reporting Status	Yes