v3.25.1
Cover page - shares
 6 Months Ended
Apr. 30, 2025
May 30, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Apr. 30, 2025  
Document Transition Report false  
Entity File Number 1-33913  
Entity Registrant Name QUANEX BUILDING PRODUCTS CORPORATION  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 26-1561397  
Entity Address, Address Line One 945 Bunker Hill Road  
Entity Address, Address Line Two Suite 900  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77024  
City Area Code 713  
Local Phone Number 961-4600  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Trading Symbol NX  
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  
Entity Central Index Key 0001423221  
Current Fiscal Year End Date --10-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   45,973,156