Document And Entity Information
3 Months Ended
Mar. 31, 2013
May 01, 2013
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2013  
Document Fiscal Period Focus Q1  
Document Fiscal Year Focus 2013  
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   6,896,366