v3.26.1
Cover - shares
 3 Months Ended
Jun. 30, 2026
Jul. 31, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 1-15240  
Entity Registrant Name JAMES HARDIE INDUSTRIES plc  
Entity Incorporation, State or Country Code L2  
Entity Tax Identification Number 98-0382260  
Entity Address, Address Line One 1st Floor, Block A  
Entity Address, Address Line Two One Park Place  
Entity Address, Address Line Three Upper Hatch Street  
Entity Address, City or Town Dublin 2  
Entity Address, Postal Zip Code D02 FD79  
Entity Address, Country IE  
City Area Code 353  
Local Phone Number 1411 6924  
Title of 12(b) Security Ordinary shares, 0.59 Euro par value per share  
Trading Symbol JHX  
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 Common Stock, Shares Outstanding   580,522,488
Amendment Flag false  
Document Fiscal Year Focus 2027  
Document Fiscal Period Focus Q1  
Entity Central Index Key 0001159152  
Current Fiscal Year End Date --03-31