v3.25.1
Cover Page - shares
 3 Months Ended
Mar. 31, 2025
Apr. 25, 2025
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2025  
Document Transition Report false  
Entity File Number 1-475  
Entity Registrant Name A. O. Smith Corporation  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 39-0619790  
Entity Address, Address Line One 11270 West Park Place  
Entity Address, City or Town Milwaukee  
Entity Address, State or Province WI  
Entity Address, Postal Zip Code 53224-9508  
City Area Code 414  
Local Phone Number 359-4000  
Title of 12(b) Security Common Stock (par value $1.00 per share)  
Trading Symbol AOS  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Amendment Flag false  
Entity Central Index Key 0000091142  
Document Fiscal Period Focus Q1  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   25,870,069
Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   116,238,973