v3.26.1
Defined Benefit Plans - Amounts Recognized in Consolidated Balance Sheets (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Jun. 30, 2025
Defined Benefit Plan Disclosure [Line Items]    
Funded status $ (243) $ (304)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:DefinedBenefitPensionPlanLiabilitiesNoncurrent    
Defined Benefit Plan Disclosure [Line Items]    
Funded status (309) (352)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent    
Defined Benefit Plan Disclosure [Line Items]    
Funded status (11) (12)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Defined Benefit Plan Disclosure [Line Items]    
Funded status 20 0
Location, Statement of Financial Position, Balance [Axis]: amcr:EmployeeBenefitAssets    
Defined Benefit Plan Disclosure [Line Items]    
Funded status $ 57 $ 60