v3.19.3
Cover
Sep. 30, 2019
Cover [Abstract]  
Document Type 8-K
Amendment Flag false
Document Period End Date Sep. 30, 2019
Entity File Number 1-33913
Entity Registrant Name QUANEX BUILDING PRODUCTS CORPORATION
Entity Central Index Key 0001423221
Entity Tax Identification Number 26-1561397
Entity Incorporation, State or Country Code DE
Entity Address, Address Line One 1800 West Loop South
Entity Address, Address Line Two Suite 1500
Entity Address, City or Town Houston
Entity Address, State or Province TX
Entity Address, Postal Zip Code 77027
City Area Code 713
Local Phone Number 961-4600
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, par value $0.01 per share
Trading Symbol NX
Security Exchange Name NYSE
Entity Emerging Growth Company false